Abstract:
A method for reusing a conductive (carbon) core/glass or sapphire cylinder test electrode comprising expelling spent core material from the tip of the electrode and refinishing the electrode tip for use in further tests and refinished test electrodes produced in accordance with the method.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a tool and method for refinishing for reuse test electrodes, particularly disk electrodes used in an evaluation process to determine the suitability of materials for predetermined applications. 
   BACKGROUND OF THE INVENTION 
   In the evaluation process to determine the suitability of materials for specified applications (such as for catalyst or reactor applications), predetermined material compositions are deposited on a testing substrate. In a typical evaluation process using electrodes to test selected material compositions for possible catalyst and other uses, a cylindrical sapphire (or other glass) surrounding a carbon core electrode is mounted in a holder, the test material under consideration is applied to or coated upon the tip of the sapphire or glass/carbon electrode, and the test is conducted. See, for example, United States Application for Patent Serial Number Ser. No. 10/757,302 filed Jan. 14, 2004 for “High Throughput Physical Vapor Deposition System for Material Combinatorial Studies” and United States Application for Patent Serial Number Ser. No. 10/800,553, filed Mar. 15, 2004 for “Holder for Sample Materials Used in High Throughput Physical Vapor Deposition Material Studies” commonly owned by the assignee of the present application. After a test, the test material on the tip surface is polished away and the carbon/sapphire electrode can be recoated with a next material for another test. When the electrode is so spent that reuse by polishing and coating is not possible, considerable expense is incurred in replacing each sapphire/carbon electrode assembly when numerous, for example, hundreds or thousands or more, test materials are evaluated. There exists a need to provide a system or device whereby expensive test electrodes can be reconfigured for reuse; thereby avoiding the expense of replacement. 
   In the prior art, no suitable means of recycling carbon core/sapphire electrodes has been found. U.S. Pat. No. 6,685,539 to Enomoto et al., discloses a processing tool to carry out a fixed-abrasive grinding process on a surface of a silicon work-piece. The processing tool includes abrasive grains made up of silica grains to provide a ground-up surface. U.S. Pat. No. 5,983,434 to Eichinger et al., discloses a rotary bristle tool for polishing or cleaning a substrate. Neither patent, however, provides an effective manner of refinishing the electrodes, when their conventional life is exhausted, as set out in this application. 
   BRIEF SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a tool and method that allows the convenient refinishing of a carbon core/glass or sapphire cylinder substrate, particularly useful with electrode materials, and to reduce the costs involved in the testing and evaluation of numerous materials. 
   The invention is described more fully in the following description of the preferred embodiment considered in view of the drawings in which: 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a side view of the expeller tool used in the invention. 
       FIG. 2  shows a cross-section of the upper portion of the tool through section  2 →← 2  shown in  FIG. 1   
       FIG. 3A  and  FIG. 3B  respectively are perspective and cross section  3 B→← 3 B views of a sapphire cylinder carbon core electrode. 
       FIG. 3C  depicts a pitted crater in the carbon element of the electrode shown in  FIG. 3A  and  FIG. 3B , rendering the electrode unuseable. 
       FIG. 4A  and  FIG. 4B  show the tool in operation expelling material from the sapphire cylinder carbon core electrode. 
       FIG. 5A  and  FIG. 5B  are enlarged cross section views through section  50 →← 50  of  FIG. 4B  showing elements of the tool while in operation. 
       FIG. 5C  is a transverse cross section view of the receptacle through section  5 C→← 5 C of  FIG. 5A . 
       FIG. 6A  shows a cross section of an electrode refinished in accordance with the invention and  FIG. 6B  shows the expelled segment removed from the electrode leaving a segment that is smoothed and polished away for reuse to a degree sufficient to match the surface of the glass cylinder. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention provides a tool and method that allows the convenient refinishing for reuse of a glass or sapphire cylinder/carbon or other conductor core electrode and comprises a tool is used to expel small increments of coating material or carbon material, with a high degree of precision from the end of the electrode. After the coating or carbon material is expelled, the electrode tip is polished until the sapphire and carbon surface is smooth again, allowing a further test material to be deposited thereon. The invention advantageously allows the use and reuse of a sapphire cylinder carbon core electrode multiple times, beyond that achieved by conventional practice of removing the test material by polishing, without need for destruction or replacement. A high level of accuracy associated with the tool accuracy enables the invention to expel very small amounts of carbon or test material with good efficiency, allowing a tip to be used many times. 
   In the invention, pitted or unusable material that renders the sapphire cylinder carbon core electrode incapable of conventional refinishing by polishing alone is expelled from a sapphire cylinder carbon core electrode. The electrode is refinished. Using a tool, the electrode tip is refinished in a method by positioning the electrode in the holder in a tool wherein the electrode and a means within the tool are concentrically aligned along a longitudinal axis in a relationship in which the spent end of the carbon element is disposed toward a receptacle fixed in place in the tool; the opposite end of the electrode is disposed in contact with a longitudinally moveable end of the tool; and the holder for the electrode is maintained in a fixed relationship with respect to the receptacle in the tool. The moveable end of the tool is incrementally extended with respect to the electrode such that the carbon core of the electrode is incrementally expelled from the holder a longitudinal distance corresponding to the extent of the spent or unusable material at the tip end of the electrode. The electrode within the holder is removed from the tool. The electrode tip is smoothed, polished and finished until the carbon element is smooth with respect to the surface of the sapphire holder. The formerly unusable test electrode with a tip surface so refinished is then capable of reuse. 
   In the side view of an example of the tool as shown in  FIG. 1 , the tool  1  essentially comprises a vice or micrometer like device having a base with ends  2  and  4  supporting a barrel  3  that rotates around shaft  5  in increments determined by corresponding external and internal threads formed in the shaft  5  and barrel  3 . A ratchet or equivalent means for effecting incremental or longitudinal movement may similarly be employed. As the barrel is rotated, the shaft extends or retracts from a predetermined longitudinal location with respect to the length of the tool. Support  6  extends from base end  4  terminating at a length where coaxially aligned shaft  9  longitudinally extends in a matching relationship with shaft  5 . Coaxially mounted on shaft  9  is a holder assembly comprising receptacle  7  and support  8  for the carbon/sapphire/holder assembly to be processed. As shown in cross section in  FIG. 5A  and  FIG. 5B , receptacle  7  includes a concentric seat for the tip holder and a recess allowing a longitudinal tolerance for the tip material expelled from the holder.  FIG. 2  shows a cross-section of the upper portion of the tool through section  2 →← 2  shown in  FIG. 1  with common elements indicated by the same reference numbers. 
     FIG. 3A  and  FIG. 3B  respectively are perspective and cross section views of a carbon/sapphire tip coaxially maintained in a cylindrical holder  30 . The carbon core is indicated at  32  enclosed on its sides within sapphire cylinder  31 . The cross section through section  3 B→← 3 B of  FIG. 3A  is shown in  FIG. 3B  where the upper end of the carbon core and glass holder are essentially in a smooth planar alignment suitable for the deposit or coating of a test material.  FIG. 3C  depicts a pitted crater  32 u in the carbon element test end of the electrode shown in  FIG. 3A  and  FIG. 3B . (The drawing figure is not to a real scale and the pitting or erosion is exaggerated for purposes of clarity in explaining the invention.) In conventional practice, the pitting or erosion  32 u at the surface renders the electrode unuseable. 
   The operation of the tool in expelling material from the electrode tip after a test is explained with reference to  FIG. 4A  and  FIG. 4B  and  FIG. 5A  and  FIG. 5B . As shown by the reference arrows  10  and  11  with respect to the tool  1  depicted in  FIG. 4A , rotation of the handle  3  results in longitudinal movement of the shaft  5  along the axis of the coaxial shafts  5  and  9 . In  FIG. 4B , the electrode assembly  30  is seated in female receiver  7 . In the cross sections of  FIG. 5A and 5B , when the specimen  30  is placed into position between shaft  5  and female relief shape  7 , the handle  3  is then rotated  10  which causes shaft  5  to extend a distance “d” from longitudinal location  51  to longitudinal location  52 , and carbon material  32   u  to be expelled from sapphire cylinder  31  of the electrode  30  a distance corresponding to “d.” Distance “d” preferably is only to the extent of the existing surface deformity such that the concentric sapphire carbon assembly. (For purposes of clarity, the relative distance between location  51  and location  52 , “d,” is exaggerated in the drawing figure, although incremental segments expelled may be made, for example, in lengths of 0.005 mm using a suitable micrometer movement.) In the longitudinal cross section detail shown in  FIG. 5A  and  FIG. 5B , receptacle  7  includes a concentric seat  50  for the electrode  30  and a narrower recess  40  allowing a longitudinal tolerance for the spent material  32   u  expelled from the holder. The transverse cross section of the receptacle  7  shown in  FIG. 5C  shows the coaxial alignment of the seat  41  and recess  40  in the receptacle  7 .  FIG. 6A  shows a cross section of an electrode  30  refinished in accordance with the invention. The carbon segment  32   rf  remaining in the sapphire cylinder  31  after the expelled segment “d” (or  32   u ) as shown in  FIG. 6B  is smoothed or ground away and polished by known means to a degree sufficient to match  32   f  the surface of the glass cylinder  31 . In certain instances, the a segment of the corresponding end surface of the cylinder holding the core may be ground away in the refinishing process to achieve a planar concentric surface for the electrode. A refinished electrode capable of many more reuses is thereby achieved which may be coated with test materials such as metals, oxides, catalysts and the like for evaluation. Specific dimensions for the diameters of the receptacle, seat and recess, and expelling increments, are essentially determined by the corresponding sizes of the tip and holder processed and the degree of surface deformation or pitting encountered. 
   Thus, firmly embedded core material is expelled from the end of a hard glass cylinder. Using a finely threaded micrometer base movement, expulsion length control is within 0.5 mm or any other desired length determined by the corresponding threads of the shaft  5  and barrel  3 . 
   Having described the invention in detail, those skilled in the art will appreciate that, given the present description, modifications may be made to the invention without departing from the spirit of the inventive concept herein described. Therefore, it is not intended that the scope of the invention be limited to the specific and preferred embodiments illustrated and described. Rather, it is intended that the scope of the invention be determined by the appended claims.