Abstract:
A coating system including a reflective cool down chamber with at least one arcuate wall; and an infrared lamp directed at the arcuate wall.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to a system for thermal barrier coatings (TBCs), and more particularly, to thermal control therein. 
         [0002]    Thermal barrier coatings (TBCs) are multilayer materials that are typically applied to hot sections of an engine to reduce the surface temperature experienced by workpieces. TBCs often include (1) a substrate, which may be an engine workpiece—typically a gamma-gamma prime superalloy (2) an aluminum rich bond coat (3) thermally grown oxide (TGO) that reduce further oxidation of bond coat by blocking oxygen (4) a low thermal conductivity ceramic top coat. 
         [0003]    One of the fabrication methods for top coat is electron beam-physical vapor deposition (EB-PVD) in which a columnar top coat microstructure develops on the surface of the workpieces in near vacuum at elevated temperatures. EB-PVD is a form of physical vapor deposition in which an ingot of material is bombarded with an electron beam given off by a charged tungsten filament under high vacuum. The electron beam causes atoms from the ingot to transform into the gaseous phase. These atoms then condense into solid form, coating the workpiece in the vacuum chamber, and within a line of sight, with a thin layer of the material. 
         [0004]    To reduce the thermal shock between the ceramic top coat and the metallic bond coat post top coating, workpieces are slowly cooled down to room temperature in a preheated oven. The aforementioned method of cool down may be time consuming and not cost effective. 
       SUMMARY 
       [0005]    A coating system according to one disclosed non-limiting embodiment of the present disclosure can include a reflective cool down chamber with at least one arcuate wall and an infrared lamp directed at the arcuate wall. 
         [0006]    A further embodiment of the present disclosure may include wherein the at least one arcuate wall includes an interior surface with a high index of reflection. 
         [0007]    A further embodiment of the present disclosure may include wherein the at least one arcuate wall includes an interior surface with a mirror finish. 
         [0008]    A further embodiment of the present disclosure may include, wherein the infrared lamp is located on a movable door that permits intake of a workpiece holder. 
         [0009]    A further embodiment of the present disclosure may include, wherein the infrared lamp is located on a movable door that permits egress of a workpiece holder. 
         [0010]    A further embodiment of the present disclosure may include a diffusion lens mounted to the infrared lamp. 
         [0011]    A further embodiment of the present disclosure may include a diffusion chamber adjacent to the reflective cool down chamber. 
         [0012]    A further embodiment of the present disclosure may include, wherein the diffusion chamber is an electron beam physical vapor deposition (EB PVD). 
         [0013]    A method coating a workpiece according to one disclosed non-limiting embodiment of the present disclosure can include moving a workpiece holder from a deposition chamber a reflective cool down chamber with at least one arcuate wall; and directing infrared energy from an infrared lamp at the arcuate wall to reduce a temperature gradient of a workpiece. 
         [0014]    A further embodiment of the present disclosure may include directing the infrared energy for 3-10 seconds. 
         [0015]    A further embodiment of the present disclosure may include diffusing the infrared energy. 
         [0016]    A further embodiment of the present disclosure may include locating the infrared lamp on a door of the reflective cool down chamber. 
         [0017]    A further embodiment of the present disclosure may include, wherein the diffusion chamber is an electron beam physical vapor deposition (EB PVD). 
         [0018]    A further embodiment of the present disclosure may include operating the infrared energy for a time in response to a thermal mass of the workpiece. 
         [0019]    The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
           [0021]      FIG. 1  is a partial schematic view of a deposition system; and 
           [0022]      FIG. 2  is a schematic view a reflective cool down chamber. 
           [0023]      FIG. 3  is a schematic view of the reflective cool down chamber operation. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 1  schematically illustrates an example system  20  for depositing coating on workpieces  22  in the interior  24  of a deposition chamber  26 . The system  20  passes the workpiece  22  downstream along a workpiece flowpath sequentially through a first load lock chamber  28  forming an in-feed chamber, a preheat chamber  30 , the deposition chamber  26 , a cool down chamber  34 , and a second load lock chamber  36 . 
         [0025]    Each of a multiple of workpieces  22  may be conveyed through the system on a workpiece holder  40  of which, depending upon implementation, may support a single workpiece or multiple workpieces. In the deposition chamber  26 , the workpiece holder  40  may be manipulated by a sting mechanism  42 . In one embodiment, a loading station  50  and an unloading station  52  are provided. These may include robots (e.g., six-axis industrial robots) to transfer fixture workpieces from and to conveyors, pallets, and the like. 
         [0026]    After deposition is complete, the sting mechanism  42  is withdrawn back through the preheat chamber  30  into the first load lock chamber  28 , such that the workpieces may be removed from the deposition chamber  26 . 
         [0027]    The exemplary deposition chamber  26  is configured for electron beam physical vapor deposition (EB-PVD). In this example, at least one electron beam (EB) gun  60  is positioned to direct its beam to one or more deposition material ingots  70 ,  72 . In this example, there are two ingots  70 ,  72  of different materials. The ingots may be ceramics of different composition for forming distinct layers in a thermal barrier coating, erosion coating, abradable coating, or abrasive coating. For example, Zirconia-based ingot examples include, but are not limited to, an yttria-stabilized zirconia (YSZ) such as 7YSZ, a gadolinia-stabilized zirconia, or an YSZ of different yttria content or dopant. 
         [0028]    With reference to  FIG. 2 , in one exemplary implementation, the reflective cool down chamber  34  provides a reflective chamber that includes an arcuate wall  100  and one or more infrared lamps  102  that have diffusing lenses  104  such that the reflective cool down chamber  34  forms an ovid-like shape. The infrared lamps  102  may, for example, be located on a movable door  108  that permits entry and/or egress of the workpiece holder  40 . The exact size and shape may be optimized such that the workpieces are cooled down slowly and uniformly. An interior surface  106  of the arcuate wall  100  provides a high index of reflection, e.g., mirror polish aluminum, stainless steel, etc. The cooling workpiece dissipates heat primarily through radiation and the reflective arcuate wall  100  of the reflective cool down chamber  34  reflects radiation back to the workpieces, thereby reducing the cooling rate. 
         [0029]    The infrared lamps  102  may be located on movable doors  108  that permit intake and egress of the workpiece holder  40 . The infrared lamps  102  increase heat to make up for heat loss to the interior surface  106  of the arcuate wall  100  and also reduce the cooling rate. The orientation of the infrared lamps  102  is configured to uniformly distribute heat to the workpieces. Thus, temperature gradients in the workpiece are significantly reduced. 
         [0030]    The diffusing lenses  104  facilitate diffusion of the radiation in a suitably wide cone to permit uniform heating. The reflective cool down chamber  34  and infrared lamps  102  may be used in conjunction with various existing coaters. The infrared lamps  102  can be turned on and off quickly, unlike a heating oven that requires a relatively long time to heat up and cool down. 
         [0031]    With reference to  FIG. 3 , the reflective cool down chamber  34  is adjacent to the deposition chamber  26  such that after the coating process is complete (step  206 ), the door  108  opens (step  202 ) such that the workpieces, which are supported by workpiece holder  40 , are moved from the deposition chamber  26  to the reflective cool down chamber  34  (step  204 ). The movable doors  108  are then closed and the infrared lamps  102  are activated (step  206 ). In one example, the infrared lamps  102  may be activated for about 3-10 seconds such that the infrared energy is provided in response to a thermal mass of the workpiece. The workpieces are then cooled within the reflective cool down chamber  34  at a suitable rate, to prevent spallation. 
         [0032]    The use of the terms “a,” “an,” “the,” and similar references in the context of description (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. 
         [0033]    Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
         [0034]    It should be appreciated that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be appreciated that although a workpiece component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. 
         [0035]    Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
         [0036]    The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.