Patent Publication Number: US-2011048871-A1

Title: Brake rotors, disk assemblies, and other components

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The current application claims the benefit of priority under 35 U.S.C. §119(e) of U.S. provisional patent application Ser. No. 61/230,625, filed on Jul. 31, 2009. 
     The current application is also a continuation-in-part of co-pending application for U.S. patent Ser. No. 12/533,933, filed on Jul. 31, 2009 and entitled “Reduction of Particulate Emissions from Vehicle Braking Systems,” and also a continuation-in-part of co-pending application for U.S. patent Ser. No. 12/195,994, filed on Aug. 21, 2008 and entitled “Brake Disk and Method of Making Same,” which claims the benefit of U.S. provisional patent application Ser. No. 60/957,422, filed on Aug. 22, 2007 and U.S. provisional patent application Ser. No. 60/971,879, filed on Sep. 12, 2007. All applications to which the current application claims priority are incorporated by reference herein in their entireties. 
    
    
     TECHNICAL FIELD 
     The subject matter described herein relates to braking systems of vehicles. For the purposes of this disclosure, the term “vehicle” includes, but is not limited to, automobiles, motorcycles, motorized scooters, on and off-road vehicles electric vehicles such as golf carts, light and heavy duty trucks, road tractors and semi-trailers, vans, off-road vehicles such as all-terrain vehicles and dune-buggies, trains, and the like. The subject matter disclosed herein is also applicable to braking systems used with aircraft landing gear, bicycles, military vehicles, and the like. 
     SUMMARY 
     In various aspects a braking system component includes a bulk structural material and a friction surface. The friction surface can include an outer coating including a corrosion and wear-resistant material that can be created in one or more custom colors based on a chemical composition of the outer coating. 
     Optional variations of these aspects can include one or more of the following features. The outer coating of the corrosion and wear-resistant material can include a first layer that includes a crystalline material and a second layer overlaying and contacting the first layer and that includes an amorphous material. The friction surface can include a plurality of raised island formations separated by channels or gaps that permit air flow to cool the rotating braking element during active engagement with the brake member. The first layer and the second layer can have an inter-layer period of less than 10 nm and the outer coating can include a super-lattice structure. The first layer can include one or more amorphous metals and the second layer can include one or more binary metals. The amorphous metal of the first layer can be selected from titanium, chromium, zirconium, aluminum, hafnium and an alloy combination thereof. The binary metal of the second layer can be selected from a metal nitride, a metal boride, a metal carbide and a metal oxide. The second layer further can include one or more nitrides, borides, carbides or oxides of the amorphous metal of the first layer. The braking system component can include a brake disk or rotor. 
     The subject matter described herein provides many advantages that can include, but are not limited to reducing the wear rate of brake system friction components without sacrificing braking performance. Additionally, the corrosion and wear-resistant coating material can be provided in a number of custom colors to coordinate with other features of a vehicle. Because the corrosion and wear-resistant coating is highly durable even under extreme conditions such as might occur during frictional braking activities, the custom color can be long lasting, potentially for as long as the useful life of the braking system component. 
     The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed embodiments. In the drawings, 
         FIG. 1  is a perspective diagram illustrating a brake disk or rotor; 
         FIG. 2  is a diagram showing a top plan view of a brake disk or rotor; 
         FIG. 3  is a diagram showing a cross-sectional view of a brake disk or rotor; 
         FIG. 4  is a diagram showing an expanded cross-sectional view of a brake disk or rotor surface; 
         FIG. 5  is a diagram showing a closer expanded cross-sectional view of a brake disk or rotor surface; 
         FIG. 6  through  FIG. 18  are diagrams showing two views each of various implementations of brake rotors and floating rotor assemblies consistent with the current subject matter; and 
         FIG. 19  is a process flow diagram illustrating a method. 
     
    
    
     Similar reference numerals in the drawings are intended to denote similar structures or other features of the described subject matter. 
     DETAILED DESCRIPTION 
     The braking system of a vehicle typically includes one or more friction components that are pressed into contact to transform kinetic energy of the motor vehicle into heat and thereby slow the vehicle. These friction components can include a wheel-mounted rotating device, such as for example a rotor (also referred to as a brake disk) or drum and a movable device such as for example a brake pad or shoe, that is moved via a braking mechanism so that a friction material on the moveable device is forcibly contacted with a friction surface of the wheel-mounted rotating device. The braking mechanism can be controlled by a user operable system, such as a foot-operated brake pedal or a hand-operated grip device and can be mechanical, electrical, or hydraulic. 
     For brake systems in which the rotating device is a rotor or a disk, the mechanism can be a set of calipers and a mechanical or hydraulic system for applying pressure to a movable device mounted to each caliper to urge it against the friction surfaces of the rotor or disk. The rotor or disk typically has two opposing friction surfaces on opposite annular faces of a disk-like structure. A central hole in the rotor or disk is configured to be mounted co-axially with the wheel. If the rotating device is a drum, the movable device can be one or more shoes. The drum is a cylindrical device whose axis is the same as that of the wheel to which it is mounted. The friction surface of the drum is on the outer rotation surface. The shoes are urged against the friction surface by calipers, levers, or other devices that are controlled by the user. 
       FIG. 1  shows an example of a brake disk or rotor  100  that has a disk-shaped body with a central hole  102  adapted so that the brake disk  100  can be positioned over the hub of a wheel (not shown) and centered on the axis of rotation  104  of the wheel and brake disk or rotor  100  assembly. The shape of the brake disk or rotor  100  and the central hole  102  are shown in  FIG. 1  as having a circular cross-section normal to the axis of rotation  104 . However, this is merely an example. The cross-section of either the brake disk or rotor  100  and the central hole  102  can be non-circular as long as they are rotationally symmetrical about the axis of rotation. Opposing annular surfaces  106  and  110  are disposed on opposite sides of the brake disk or rotor  100  and can extend from the outer periphery  112  of the brake disk or rotor  100  to the central hole  102 . At least a portion of each of the annular surfaces  106  and  110  serves as a friction surface against which the friction material of the brake pads or shoes is urged during braking. A corrosion resistant coating can be applied to the friction surfaces as described in more detail below. 
     In some implementations, the friction surfaces disposed on annular surfaces  106  and  110  of brake disk or rotor  100  include a plurality of raised land portions or island formations  202  with spaced air flow channels  204  between the island formations  202 . Only the raised portions of the island formations contact the brake pads or shoes during braking in this arrangement, and comprise the wear surfaces of the brake disk or rotor  100 .  FIG. 2  shows a face-on view of a brake disk or rotor looking from above at one of the annular surfaces  106  that includes some examples of possible land portions or island formations  202  on the friction surface. In  FIG. 2 , four different possible island formations  202  are shown in each of four quadrants of an annular surface  106  of a brake disk or rotor  100 . The arrangement of the island formations  202  shown in  FIG. 2  is for illustrative purposes. In general, a uniform pattern is used throughout the friction surface of an annular surface  106  of a brake disk or rotor  100 . In some implementations, however, a combination of the features shown or other comparable surface features can be included. As shown in  FIG. 2 , the island formations  202  can include tear drop shaped formations  202   a , circle or dot shaped formations  202   b , figure eight shaped formations  202   c , and letter shaped formations  202   d , with channels or voids  204  between and/or around the island formations allowing air flow extending between the formations. As seen in three of the quadrants in  FIG. 2 , the island formations  202  can be arranged in rows which extend radially from the central opening  102  of the brake disk or rotor  100  out to the peripheral edge  112 , with radial air flow channels  204  extending outwardly between each adjacent pair of rows of island formations  202 , in addition to channels which extend between adjacent pairs of island formations  202  in each row. 
       FIG. 3  shows a side cross sectional view of a brake disk or rotor  100  with the cross section taken along a diameter of the annular surfaces  106  and  110 . As shown in  FIG. 3 , the island formations  202  have upper surfaces  302  which are at least substantially flat friction surfaces for contact with the brake pads or shoes during braking, and are designed with sufficient surface areas for braking purposes. Shapes and configurations of island formations  202  that differ from those shown in  FIG. 2  and  FIG. 3  can also be used, including but not limited to squares, trapezoids, rectangles, triangles, stars, letters or names, numbers, logos, trademarks, dashes, other geometric shapes, and the like, with or without rounded corners, can also be used to improve cooling and wear, to meet specific performance criteria, and/or to improve the aesthetic appearance of the brake disk or rotor  100 . 
     Spaced island formations  202  arranged in a pattern to create cooling air channels and gaps  202  can be arranged to extend over an entire annular surface  106  and  110  of a brake disk or rotor  100 . Alternatively, island formations  202  of any desired different shapes and sizes may be provided in patterns over the disk surface. The shape and positioning of the island formations  202  can be designed to be aesthetically pleasing in appearance which is particularly desirable when the disk surfaces are externally visible, as is the case with many motor cycle brake disks. The grooves or channels around the island formations  202  result in a significant reduction in the overall weight of the brake disk or rotor  100  which in turn improves the efficiency and performance of the motor vehicle. Additionally, the channels and gaps  204  allow for air flow around the island formations  202  for increased cooling and heat dissipation. The base of each channel or gap  204  can optionally be roughened or modulated to provide bumps or the like that create turbulence in air flow along the channel or gap  204  which can also improve the cooling effect. 
     Island formations  202  of desired shapes and dimensions can be formed in any suitable manner, for example by appropriate machining or other forming processes. After machining, the desired island formations  202  on one or both annular surfaces  106  and  110  of the brake disk or rotor  100 , the entire annular surface  106  of the brake disk or rotor  100  can be coated with a wear and corrosion resistant coating  402  which eliminates or greatly reduces the wear of the braking surfaces  302  of the island formations  202 .  FIG. 4  shows an expanded view  400  of a portion of the annular surface  106  of a brake disk or rotor  100  with island formations  302  and air flow channels or gaps  204 . In  FIG. 4 , the wear and corrosion resistant coating  402  is deposited on the upward facing surfaces  302  of the island formations  202  and also in the air flow channels or gaps  204 . Alternatively, the island braking surfaces alone can be coated with the wear and corrosion resistant coating  402 . During the process of forming the wear and corrosion resistant coating  402 , surface in addition to those shown as having the wear and corrosion resistant coating  402  in  FIG. 4  can also be coated, either deliberately or incidentally. For example, the wear and corrosion resistant coating  402  can be deposited on the walls of the island formations  202 , which are shown as vertical lines in  FIG. 4 . The wear and corrosion resistant coating  402  can improve the overall look or aesthetics of the brake disk or rotor  100 . 
     In one implementation, the wear and corrosion resistant coating  402  includes a first layer of a metal, such as a pure titanium metal, and a second layer that includes a nitride, boride, carbide or oxide of the metal used in the first layer. The coating can be applied using a physical vapor deposition source such as a cathodic arc source with a controlled gas atmosphere. The materials used for the wear and corrosion resistant coating  402  can be of different colors and can be designed to produce different surface appearances, such as a light reflective, shiny appearance, for example, particularly on regions of the annular surfaces  106  and  110  that are visible when the brake disk or rotor  100  is installed on a vehicle. 
     A surface finish can be produced on the annular surfaces  106  and  110  of the brake disk or rotor  100  substrate, including the island formations  202 , by blasting the annular surfaces  106  and  110  with a continuous stream of particles (commonly referred to as bead blasting) which are typically harder than the annular surfaces  106  and  110 . These particles can be round and/or smooth in shape or alternatively very irregular in shape. Various particle shapes can be used to impart a different surface finish or surface geography to the brake disk or rotor  100 . For example, with round particles (of various sizes) and appropriate particle energy (air pressure or hydro pressure) a surface texture that microscopically resembles low soft rolling hills can be achieved. With irregular (crystalline) shaped particles, a very coarse surface geometry (very rugged/jagged peaks and valleys) can be imparted to the brake disk or rotor  100  surfaces. Other methods such as a sanded or a ground surface finish can be used to give a different appearance when coated with the wear and corrosion resistant coating  402 . When the sanded or ground surface finish is done in a cross-hatched configuration and then coated with the wear and corrosion resistant coating  402 , the coated brake disk or rotor  100  can be made to look as though it has a woven appearance such as is found in components made from carbon fiber. 
     In general, there are a multitude of surface finish techniques that can be utilized to impart a specific surface texture or geometry into the brake disk or rotor  100  prior to application of a wear and corrosion resistant coating  402 . In one implementation, selected surface finishes can be implemented as described in co-pending U.S. patent application Ser. No. 12/034,590 filed on Feb. 20, 2008, the entire contents of which are incorporated herein by reference. In alternative variations, only the braking surfaces  302  of the island formations  202  are treated to produce a surface texture, for example, by masking the channels or gaps  204  between the island formations  202  during bead blasting or other surface treatments. 
     The substrate forming the bulk of the brake disk or rotor  100  can include any suitable material, including but not limited to cast iron, stainless steel, light weight metal alloys, ceramic materials, ceramic composite materials, titanium, or combinations thereof. The wear and corrosion resistant coating  402  can optionally be applied using the fixtures, techniques and materials as described in co-pending application Ser. No. 12/034,590 referenced above, and in co-pending U.S. patent application Ser. No. 12/034,599 on Feb. 20, 2008, the entire contents of which are incorporated herein by reference. 
     As shown in  FIG. 5 , which is a very expanded view  500  of an island formation  202  of a brake rotor or disk  100 , the wear and corrosion resistant coating  402  sits upon the a braking surface  302  prepared as described above. The wear and corrosion resistant coating  402  can include a first layer  502  of a material having an amorphous structure (i.e. a non-crystalline structure) or a crystalline structure. This first layer  502  is applied directly onto the prepared braking surface  302 . The amorphous or crystalline material can in some implementations be a metal such as titanium, chromium, zirconium, aluminum, hafnium or an alloy thereof. The wear and corrosion resistant coating  402  further includes a second layer  504  that overlays and contacts the first layer  502 . Though the layers are depicted as distinct in  FIG. 5 , in some implementations, the first layer  502  and the second layer  504  intermingle or merge such that no distinct boundary exists between them. The second layer  504  can in some variations include one or more binary metals, for example, one or more metal nitrides, metal borides, metal carbides and metal oxides. The second layer  504  can alternatively or additionally include one or more nitrides, borides, carbides or oxides of the metal used in the first layer  502 . In some implementations, the wear and corrosion resistant coating  402  can include more than two layers of alternating metal and metal compound materials that are applied in order to impart specific physical properties to the brake disk or rotor  100 . In some implementations of a wear and corrosion resistant coating  402 , the first layer  502  can include amorphous titanium and the second layer  504  can include a titanium nitride (TiN, Ti.sub.2N, etc.). Multiple alternating instances of the first layer  502  and the second layer  504  can be configured to form a lattice structure or a super lattice structure that includes thin films formed by alternately depositing two different components to form layered structures. Multilayers become superlatices when the period of the different layers is less than about 10 nm (100 Angstroms). With this cooperation of structure, a wear and corrosion resistant coating  402  having a service life to exceed approximately 100,000 vehicle miles or more can be obtained. it should be noted that abbreviations (e.g. TiN, Ti.sub.2N, etc.) are used herein as a shorthand rather than an exact chemical label, and do not suggest that the stoichiometry of the indicated compound must be exactly as stated in the abbreviation. 
     As shown in  FIG. 5 , the contact surface  302  of the island formation  202  can be prepared with a roughened surface treatment prior to application of the first layer  502  of the wear and corrosion resistant coating  402 . This pre-roughening treatment is optional, and can be imparted by blasting the annular surface  106  and  110  of the brake disk or rotor  100  with irregular shaped particles, as described above, such that the braking surface  302  includes a series of peaks and valleys with angular and irregular apexes at each peak and valley. Alternative surface textures may be rounded, cross-hatched, or woven in appearance, as described above. When a braking surface  302  prepared in this manner is subsequently coated with one or more coating layers of the wear and corrosion resistant coating  402 , the resultant, substantially flat surface can exhibit a three dimensional appearance or woven texture. In addition, the composition and thickness of the layers forming the wear and corrosion resistant coating  402  can be selected to achieve desired light reflection and absorption characteristics in order to produce an attractive ornamental appearance that can include one or more ornamental colors. 
     As noted above, the island formations  202  or raised land portions on the annular surfaces  106  and  110  of a brake disk or rotor  100  can facilitate cooling of the brake disk or rotor  100  by increasing and directing air flow around and between the island formations during braking. By increasing the ability of the brake disk to dissipate heat, the risk of brake fade, wear and warpage is reduced, and can increase the effective service life of the brake disk or rotor. In addition, the channels or gaps  204  between adjacent island formations  202  reduce the overall weight of the brake disk or rotor  100 , reducing the amount of material required. Finally, the island formations  202  can be designed to produce a visually attractive appearance in the visible portion of the brake disk, adding to the overall look of a vehicle such as a motor cycle where the brake disks are clearly visible. 
     Furthermore, brake disks or rotors  100  as well as brake drums prepared as described herein also offer distinct advantages in wear rates of brake pads or shoes used together with the brake disks or rotors  100  or brake drums. Braking performance equal to or greater than that of brake disks or rotors without the wear and corrosion resistant coating  402  is achieved using standard brake pads and brake disks or rotors that include the wear and corrosion resistant coating  402 . In addition, the brake disk or rotor  100  with the wear and corrosion resistant coating  402  experiences a much slower wear rate than a brake disk or rotor  100  without the wear and corrosion resistant coating  402 . Furthermore, the wear rate of the brake pads or shoes used in a braking system with a brake disk or rotor  100  with a wear and corrosion resistant coating  402  such as described herein is also substantially reduced, in some examples providing a functional lifetime of the brake pads or shoes that is 50% to 500% longer than that of the brake pads or shoes used in a braking system with a standard brake disk or rotor that does not have a wear and corrosion resistant coating  402  according to the current subject matter. In other examples, the wear rate of the brake pads or shoes used in a brake system with a brake disk or rotor  100  or a brake drum whose friction surfaces have a wear and corrosion resistant coating  402  and/or a plurality of island formations  202  as described herein can be reduced to no more than approximately 90% of the wear rate of the same brake pads or shoes used with a standard brake disk or rotor or a standard brake drum. In further implementations, the wear rate of the brake pads or shoes used in conjunction with a brake disk or rotor  100  or a brake drum whose friction surfaces have a wear and corrosion resistant coating  402  and/or a plurality of island formations  202  as described herein can be reduced to a range of approximately 20% to 40% of the wear rate of the same brake pads or shoes used with a standard brake disk or rotor or a standard brake drum. 
     Brake rotors according to the current invention were tested using a standard dynamometer test schedule which is summarized in Table 1. The test includes 14 sections or phases, which are listed in the first column of Table 1. The characteristics of each section or phase of the test are summarized based on number of stops in the section or phase, initial speed of the vehicle prior to each stop, final speed of the vehicle after each stop, pressure applied between the brake pads and the rotor, and the rate of deceleration. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Dynamometer Test Schedule 
               
            
           
           
               
               
               
               
               
               
            
               
                 Section or 
                 # of 
                 Initial Speed 
                 Final Speed 
                 Pressure 
                 Deceleration 
               
               
                 Phase 
                 Stops 
                 (MPH) 
                 (MPH) 
                 (psi) 
                 (ft · s −2 ) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Green 
                 9 
                 20 
                 0 
                 100-900 
                   
               
               
                 Effectiveness 
                 9 
                 40 
                 0 
               
               
                 Burnish 
                 200 
                 40 
                 0 
                   
                 9.0 
               
               
                 First 
                 9 
                 20 
                 0 
                 100-900 
               
               
                 Effectiveness 
                 9 
                 40 
                 0 
                 100-900 
               
               
                   
                 9 
                 60 
                 0 
                 100-900 
               
               
                   
                 9 
                 90 
                 0 
                 100-900 
               
               
                 First Fade 
                 10 
                 60 
                 0 
                   
                 9.0 
               
               
                 First 
                 12 
                 30 
                 0 
                   
                 9.0 
               
               
                 Recovery 
               
               
                 Reburnish 
                 35 
                 40 
                 0 
                   
                 9.0 
               
               
                 Second 
                 9 
                 20 
                 0 
                 100-900 
               
               
                 Effectiveness 
                 9 
                 40 
                 0 
                 100-900 
               
               
                   
                 9 
                 60 
                 0 
                 100-900 
               
               
                   
                 9 
                 90 
                 0 
                 100-900 
               
               
                 Second Fade 
                 10 
                 60 
                 0 
                   
                 9.0 
               
               
                 Second 
                 12 
                 30 
                 0 
                   
                 9.0 
               
               
                 Recovery 
               
               
                 Third 
                 9 
                 20 
                 0 
                 100-900 
               
               
                 Effectiveness 
                 9 
                 40 
                 0 
                 100-900 
               
               
                   
                 9 
                 60 
                 0 
                 100-900 
               
               
                   
                 9 
                 90 
                 0 
                 100-900 
               
               
                 Wet 
                 9 
                 20 
                 0 
                 100-900 
               
               
                 Effectiveness 
                 9 
                 40 
                 0 
                 100-900 
               
               
                   
                 9 
                 60 
                 0 
                 100-900 
               
               
                   
                 9 
                 90 
                 0 
                 100-900 
               
               
                 Low Energy 
                 500 
                 40 
                 0 
                   
                 7.0 
               
               
                 Durability 
               
               
                 High Energy 
                 500 
                 60 
                 0 
                   
                 9.0 
               
               
                 Durability 
               
               
                 Final 
                 9 
                 20 
                 0 
                 100-900 
               
               
                 Effectiveness 
                 9 
                 40 
                 0 
                 100-900 
               
               
                   
                 9 
                 60 
                 0 
                 100-900 
               
               
                   
                 9 
                 90 
                 0 
                 100-900 
               
               
                   
               
            
           
         
       
     
     Table 2 summarizes the results of tests according to the protocol summarized in Table 1 with Hawk Organic rotors. Identical Hawk Organic Pads (Model No. RGHP44002G) available from Wellman Products Group of Akron, Ohio) were tested under similar conditions using the protocol of Table 1. The first pad was tested with a polished but uncoated rotor that does not have a wear and corrosion resistant coating  402  or island formations  202  according to the current subject matter. The second pad was tested with a brake disk  100  having a wear and corrosion resistant coating  402  with a polished finish on the friction surfaces of the rotor  100 . The brake pad used in these tests was analyzed using an Oxford Handheld Metal Analyzer that determines composition using X-ray fluorescence (model no. X-MET5100, available from Oxford Instruments U.S.A. of Scotts Valley, Calif.). The determined composition by mass was approximately 21.4% zirconium, 16.4% zinc, 13.7% iron, 0.55 strontium, 20.9% titanium, 13.9% copper, and 13.1% antimony. 
     As shown in Table 2, the pad tested with the rotor that included a wear and corrosion resistant coating  402  on the friction surfaces of the rotor  100  according to implementations of the current subject matter experienced approximately 90% less loss of mass in the performance test, better than 30% less wear by mass in the low energy durability test, and approximately 85% less wear by mass in the high energy durability test. The rotor with the wear and corrosion resistant coating  402  experienced a nearly statistically insignificant loss of mass—at least 98% slower mass wear rate than the uncoated rotor. The thickness of the rotor with the wear and corrosion resistant coating  402  also decreased in thickness by amount that was smaller than the resolution of the instruments and that was at least 95% less than that of the uncoated rotor. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Results of testing of uncoated and coated rotors. 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 Performance 
                 Low Energy 
                 High Energy 
                   
               
               
                   
                   
                 Test (Pad 
                 Durability 
                 Durability 
               
               
                 Test System 
                   
                 Wear) 
                 (Pad Wear) 
                 (Pad Wear) 
                 Rotor Wear 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Hawk Pad 
                 Wear (inches) 
                 0.0515 
                 0.0057 
                 0.299 
                 0.0011 
               
               
                 with 
                 Weight Loss 
                 3.1 
                 1.1 
                 5.2 
                 6.3 
               
               
                 Uncoated 
                 (grams) 
               
               
                 Rotor 
               
               
                 Hawk Pad 
                 Wear (inches) 
                 0.0025 
                 0.0043 
                 0.0026 
                 0.00004 
               
               
                 with Rotor 
                 Weight Loss 
                 0.3 
                 0.8 
                 0.8 
                 0.1 
               
               
                 according to 
                 (grams) 
               
               
                 current 
               
               
                 subject 
               
               
                 matter 
               
               
                   
               
            
           
         
       
     
     The subject matter disclosed herein also includes both solid and floating rotor designs for a brake rotor or disk assembly. In general, a solid rotor design is one in which the rotor is cast, molded or machined in a single piece that bolts directly to the wheel or drive plate of the vehicle. A floating rotor is typically cast, molded or machined in two pieces. An outer, annular part (typically referred to as the “friction ring”) has a first central opening within which an inner part (typically referred to as the “carrier or hub”) is positioned. The inner part has a second central opening for mounting of the brake and disk rotor assembly on a wheel hub. The inner part and outer parts are attached in a non-rigid fashion by a series of buttons that are positioned about the outer circumference of the inner part and the outer part. The buttons protrude above and below the circular faces. Typically these buttons are spring-loaded in order to allow the friction ring to center itself with the brake caliber. The inner part includes lug nut holes to match with wheel lug nuts or mounting hardware on a wheel hub to which the brake rotor or disk assembly is installed. 
       FIG. 6  to  FIG. 13  each show front and side views of floating rotor assemblies. Each of these assemblies is based on a combination of an inner part or carrier and an outer part or rotor as described above.  FIGS. 6A ,  7 A,  8 A,  9 A,  10 A,  11 A,  12 A, and  13 A each show one of the circular faces of the brake rotor or disk assembly. The opposite circular face for each brake rotor or disk assembly is a mirror image of the view shown.  FIGS. 6B ,  7 B,  8 B,  9 B,  10 B,  11 B,  12 B, and  13 B each show an edge view of the brake rotor or disk assembly. Other edges can be similar. However, the relative positions of the protruding buttons in each edge view can vary slightly depending on the angle of the view. 
     Three inner part or carrier configurations are shown in  FIGS. 6-13 .  FIG. 6  and  FIG. 7  show a “star” configuration for the inner part;  FIG. 8 ,  FIG. 9 ,  FIG. 12 , and  FIG. 13  each show an “orbit” configuration for the inner part; and  FIG. 10  and  FIG. 11  show a “pulsar” configuration for the inner part. 
     The “star” configuration for the inner part is circular in shape with approximately semicircular notches disposed about the circumference to accept the buttons. A non-circular opening is included between each pair of lug nut holes to provide an open appearance. 
     The “orbit” configuration for the inner part is circular in shape with a first set of approximately semicircular notches disposed about the circumference to accept the buttons. A second set of larger and approximately semicircular notches are also disposed about the circumference and positioned between each pair of notches for accepting the buttons. A first set of circular holes are disposed such that each is centered along one of a first set of radii that are directed at each of the notches for accepting the buttons. A second set of smaller holes are disposed such that each is centered along one of a second set of radii that are directed at each of the set of larger, approximately semicircular notches. The lug nut holes in the orbit configuration are disposed such that each is centered along one of the second set of radii. 
     The “pulsar” configuration for the inner part is circular in shape with approximately semicircular notches disposed about the circumference to accept the buttons. A rounded slot and a circular hole pattern are arranged directed inwardly toward the center of the inner part from each of the notches for accepting the buttons. 
       FIG. 6 ,  FIG. 7 , and  FIG. 13  show a first configuration for the outer part having a circular central opening that includes a pattern of alternating larger and smaller approximately semicircular cutouts. The smaller cutouts accept the buttons when the first configuration of the outer part is assembled to or with one of the inner parts. The larger cutouts are arranged to match up to form approximately circular holes when this first outer part is combined with the “orbit” rotor to form the rotor or disk assembly shown in  FIG. 13 . With the “star” and “pulsar” configurations of the inner part, the larger semicircular notches of the second configuration of the outer part merely form approximately semicircular holes when the rotor or disk assembly is completed as shown in  FIG. 6  and  FIG. 8 , respectively. The first configuration for the outer part also includes pass-through holes disposed in a repeating pattern around the outer part between the annular central hole and the outer peripheral edge. 
       FIG. 8 ,  FIG. 9 , and  FIG. 10  show a second configuration for the outer part having a circular central opening that includes a pattern of alternating larger and smaller approximately semicircular cutouts. The smaller cutouts accept the buttons when the second configuration of the outer part is assembled to or with one of the inner parts. The larger cutouts are arranged to match up to form approximately circular holes when this first outer part is combined with the “orbit” rotor to form the rotor or disk assembly shown in  FIG. 11 . With the “star” and “pulsar” configurations of the inner part, the larger semicircular notches of the second configuration of the outer part merely form approximately semicircular holes when the rotor or disk assembly is completed as shown for example in  FIG. 10  for the “pulsar” configuration of the inner part. The second configuration for the outer part also includes pass-through holes disposed in a repeating pattern around the outer part between the annular central hole and the outer peripheral edge. The pass-through holes of the outer parts shown in  FIG. 8 ,  FIG. 9 , and  FIG. 10  have more holes than the first configuration for the outer part as shown in  FIG. 6 ,  FIG. 7 , and  FIG. 13 . 
       FIG. 11  and  FIG. 12  show a third configuration for the outer part having a circular central opening that includes a pattern of alternating larger and smaller approximately semicircular cutouts. The smaller cutouts accept the buttons when the third configuration of the outer part is assembled to or with one of the inner parts. The larger cutouts are arranged to match up to form approximately circular holes when this first outer part is combined with the “orbit” rotor to form the rotor or disk assembly shown in  FIG. 12 . With the “star” and “pulsar” configurations of the inner part, the larger semicircular notches of the third configuration of the outer part merely form approximately semicircular holes when the rotor or disk assembly is completed as shown for example in  FIG. 16  for the “pulsar” configuration of the inner part. The third configuration for the outer part does not include pass-through holes disposed in a repeating pattern around the outer part as in the first and the second configurations of the outer part. 
       FIGS. 14-16  show examples of a rigid rotor having different color coatings or textures as discussed below. Lug nut holes are arranged in an evenly spaced radial pattern about the central hole. A larger circular hole is disposed along a radius the passes between each pair of the lug nut holes. A pattern of smaller pass-through holes is disposed in a repeating pattern closer to the outer edge of the rotor. 
       FIG. 17  and  FIG. 18  show side and edge plan views of an additional rotor design that includes an atomic orbital pattern.  FIG. 17A  and  FIG. 17B  are the facing and edge plan views of a floating brake rotor or disk assembly in which the outer part includes the atomic orbital pattern as shown. The atomic orbital pattern is formed on the surface of the outer part as grooves cut into the faces. The opposite face of the assembly is a mirror image of that shown in  FIG. 17A . The outer part shown in  FIG. 17A  is used in conjunction with the “star” inner part discussed above. Any of the other configurations for the inner part can also be used. 
       FIG. 18A  and  FIG. 18B  are the facing and edge plan views of a rigid brake rotor that includes the atomic orbital pattern as shown. The atomic orbital pattern is formed on the surface of the outer part as grooves cut into the faces. The opposite face of the assembly is a mirror image of that shown in  FIG. 18A . Lug nut holes are disposed in a radial pattern about the central hole for the wheel hub. 
     The components of the brake rotor or disk assembly include a coating that can have a metallic appearance. For rigid rotors as shown in  FIGS. 14-16  and  FIG. 18 , the coating can be uniformly applied to the entire rigid rotor. The lug nuts used with the rigid rotor can have either a matching or a complementary color to that of the rotor. For floating rotors such as those shown in  FIG. 6  to  FIG. 13 , the inner part, the outer part, the buttons, and the lug nuts can be colored in any foreseeable combination of the coating colors. The coating colors include a polished gold, a polished chrome, a polished light gold, a satin gold, and a satin chrome. The surfaces of the outer and optionally of the inner parts can also be treated prior to application of the coating so as to have a textured appearance or even to include one or more word, letter, number, or logo characters or a combination thereof such as for example those shown in  FIG. 7 . The buttons and the lug nuts as well as other braking system components can also be treated prior to application of the coating so as to have a textured appearance or even to include one or more word, letter, number, or logo characters or a combination thereof. 
     In further implementations, a brake rotor assembly can include one or more colored finishes presented on the inner part, the outer part, and the buttons. These colored finishes can optionally be created using a wear-resistant coating such as those described above and in the priority applications whose benefit is claimed above and which have been previously incorporated by reference. Any one-piece rotor, including but not limited to those shown in the attached figures, can be presented in colors including gold, light gold, chrome, black, red, mauve, gray, dark gray, pink, green, blue, and others. Each color can be presented in a polished or a satin finish. 
     The use of different colored finishes on the different parts of a brake rotor assembly can provide the ability to vary the décor of a previously solely utilitarian component of a vehicle. Because a floating rotor can be disassembled and reassembled using the proper tools, a user can easily change the friction ring (outer part), the carrier (inner part), and/or the buttons of the brake rotor assembly relative to the other parts to create a new appearance without the need to purchase an entirely new rotor assembly. In some implementations, a brake rotor system can include one or more inner parts, optionally of different colors, provided in conjunction with one or more outer parts, also optionally of different colors, and one or more sets of buttons, also optionally of different colors. For example, if the brake rotor system included two differently colored outer parts, a single inner part, and two different colored sets of buttons, the end-user could create four unique appearances. Inclusion of a second differently colored inner part doubles the available color scheme choices to eight. Brake rotor components including wear-resistant coatings, such as those described herein and in the incorporated priority documents, have a much longer useful lifetime than conventional brake rotor components. From a manufacturer&#39;s or a retailer&#39;s standpoint, this can lead to reduced future sales of such braking components from existing customers. If the parts do not wear out or if they wear out substantially more slowly than previously available parts, the customer has no reason to purchase replacements. However, providing a user with the ability to vary the color scheme of his or her rotor assembly or of other parts of the braking system without having to purchase an entire new rotor assembly can drive added purchases of one or more baking system components and thereby increase product sales. 
       FIG. 19  shows a process flow chart  19  illustrating a method consistent with this implementation. At 1902, a rotating braking element is installed as part of a vehicle braking system. The rotating braking element includes a first component and a second component. The first component includes a first outer coating that includes a corrosion and wear-resistant material. The first outer coating includes a first decorative color whose color and original appearance are substantially retained after repeated uses of the vehicle braking system in stopping or slowing the vehicle. The second component includes a second outer coating that includes the corrosion and wear-resistant material. The second outer coating includes a second decorative color whose color and original appearance are substantially retained after repeated uses of the vehicle braking system in stopping or slowing the vehicle. At 1904, the second component s replaced with a structurally similar third component. The third component includes a third outer coating that includes the corrosion and wear-resistant material, the third outer coating includes a third decorative color whose color and original appearance are substantially retained after repeated uses of the vehicle braking system in stopping or slowing the vehicle. 
     While the first and the second colors can be the same, the third color differs from the second color. The first component and the second and third components can be any part of a braking system on a vehicle, including but not limited to solid rotors, inner or outer parts of a floating rotor assembly, lug nuts, buttons, calipers, structural supports, or the like. The colors for each of the first, second, and third components can be selected from those listed elsewhere in this document as well as from other colors. 
     The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and/or variations may be provided in addition to those set forth herein. For example, the implementations described above may be directed to various combinations and subcombinations of the disclosed features and/or combinations and subcombinations of several further features disclosed above. In addition, the logic flow depicted in the accompanying figures and/or described herein do not require the particular order shown, or sequential order, to achieve desirable results. Other embodiments may be within the scope of the following claims.