11444649 (B.P.A.I. Mar. 18, 2011)

Ex Parte Zhao

Board of Patent Appeals and InterferencesMar 18, 2011

11444649 (B.P.A.I. Mar. 18, 2011)

UNITED STATES PATENT AND TRADEMARK OFFICE UNITED STATES DEPARTMENT OF COMMERCE United States Patent and Trademark Office Address: COMMISSIONER FOR PATENTS P.O. Box 1450 Alexandria, Virginia 22313-1450 www.uspto.gov APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO. 11/444,649 05/31/2006 Yusheng Zhao S-109,087 5761 35068 7590 03/18/2011 LOS ALAMOS NATIONAL SECURITY, LLC LOS ALAMOS NATIONAL LABORATORY PPO. BOX 1663, LC/IP, MS A187 LOS ALAMOS, NM 87545 EXAMINER BODAWALA, DIMPLE N ART UNIT PAPER NUMBER 1743 MAIL DATE DELIVERY MODE 03/18/2011 PAPER Please find below and/or attached an Office communication concerning this application or proceeding. The time period for reply, if any, is set in the attached communication. PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE ________________ BEFORE THE BOARD OF PATENT APPEALS AND INTERFERENCES ________________ Ex parte YUSHENG ZHAO ________________ Appeal 2010-003634 Application 11/444,649 Technology Center 1700 ________________ Before CATHERINE Q. TIMM, LINDA M. GAUDETTE, and MARK NAGUMO, Administrative Patent Judges. NAGUMO, Administrative Patent Judge. DECISION ON APPEAL1 1 The two-month time period for filing an appeal or commencing a civil action, as recited in 37 C.F.R. § 1.304, or for filing a request for rehearing, as recited in 37 C.F.R. § 41.52, begins to run from the “MAIL DATE” (paper delivery mode) or the “NOTIFICATION DATE” (electronic delivery mode) shown on the PTOL-90A cover letter attached to this decision. Appeal 2010-003634 Application 11/444,649 2 A. Introduction2 Yusheng Zhao (“Zhao”) timely appeals under 35 U.S.C. § 134(a) from the final rejection3 of the sole claim in the 649 Application. We have jurisdiction. 35 U.S.C. § 6. We REVERSE. The subject matter on appeal relates to a method for preparing a uniformly dense diamond-silicon carbide composite in which a powder comprising diamond powder and amorphous silicon powder is consolidated at high pressure and high temperature. According to the 649 Specification, the surface carbon on the diamond particles reacts with the amorphous silicon, forming nanostructured silicon carbide, which is believed to bond the diamond grains together in a way that enhances the fracture toughness and hardness of the composite, perhaps by removing surface defects on the diamond. (Spec. 5, ll. 3-13.) Prior art composites, which are said to be composed of microcrystalline diamond held together by microcrystalline SiC, are also said to have relatively low fracture toughness (< 6 MPa·m1/2). (Id. at 1, ll. 24-27.) Prior art composites having high fracture toughness have been reported, but they are said to lack uniform density. (Id. at 1, l. 22, 2 Application 11/444,649, Diamond-Silicon Carbide Composite and Method, filed 31 May 2006, and claiming the benefit as a continuation-in- part, a prior application filed 19 April 2005 (now U.S. Patent 7,060,641), and its parent application filed 30 May 2003 (now U.S. Patent 6,939,506). The specification is referred to as the “649 Specification,” and is cited as “Spec.” The real party in interest is listed as Los Alamos National Security, LLC (Appeal Brief, filed 13 July 2009 (“Br.”), 2.) 3 Office action mailed 26 November 2008. Appeal 2010-003634 Application 11/444,649 3 to 2, l. 14.) Composites of the invention are said to be uniformly dense and to have a fracture toughness > 8 MPa·m1/2. (Id. at ll. 24-28.) The claim reads: A method for preparing an uniformly dense diamond-silicon carbide composite, comprising consolidating a powder mixture of diamond and amorphous silicon at a pressure and temperature sufficient to produce a uniformly dense diamond-silicon carbide composite having a Vickers hardness of at least 36 GPa, a Knoop hardness of at least 28 GPa, and a fracture toughness of at least 8 MPa·m1/2. (Br., Claims App.) The Examiner has maintained the following ground of rejection:4 The claim stands rejected under 35 U.S.C. § 103(a) in view of the combined teachings of Ringwood5 and Kosuzu.6 4 Examiner’s Answer mailed 16 October 2009 (“Ans.”). 5 Alan E. Ringwood, Production of Diamond Compacts Consisting Essentially of Diamond Crystals Bonded by Silicon Carbide, U.S. Patent 5,010,043 (1991). 6 Takeshi Kosuzu et al., Electrode Material for Rechargeable Lithium Battery, &c., U.S. Patent Application Publication US 2003/0157407 A1 (21 August 2003). Appeal 2010-003634 Application 11/444,649 4 B. Discussion Findings of fact throughout this Opinion are supported by a preponderance of the evidence of record. Zhao argues that the Examiner has failed to establish a reason for Ringwood to ball mill a mixture of diamond and silicon powders long enough to convert the silicon to amorphous silicon. (Br. 5.) Zhou finds, and the Examiner does not dispute, that Ringwood only describes using the mill to provide an intimate mixture of the silicon and diamond power, and that Ringwood is silent regarding amorphous silicon or its production by ball milling. (Id.) Moreover, the Examiner does not dispute Zhou’s finding that Kosuzu does not describe how long the silicon must be ball milled to transform the silicon to amorphous silicon. (Id.; Kosuzu 6 [0076].) According to Zhou, the time required to achieve substantially complete conversion is about 11 hours. (Id.; Spec. 8, l. 10-11.) In the absence of a reason to perform such an extended milling operation, Zhou argues, it would not make sense to mill for such a long time only to mix the powders. (Id.) The Examiner maintains that upon ball milling the silicon and diamond mixture, followed by the sintering process taught by Ringwood, “a uniformly dense composite is obviously formed” having the properties recited in the claim. (Ans. 5, last para.) The Examiner does not cite any credible evidence that supports this conclusion. The Examiner also argues that upon ball milling the diamond/silicon particle mixture, “amorphous silicon powder is obviously provided in the mixture.” (Id.) While it is not unreasonable on its face that some amorphous silicon may be formed, the Examiner has not directed our attention to any credible evidence that Appeal 2010-003634 Application 11/444,649 5 sufficient amorphous silicon powder is formed by ordinary ball milling to result in a diamond-silicon carbide composite having the recited properties. Ringwood teaches that “silicon films are often vitreous and therefore less dense than silicon powder.” (Ringwood, col. 8, l. 68, to col. 9, l. 1.) In light of this disclosure, it appears that Ringwood provided ordinary (i.e., not amorphous) silicon powder with the silicon-coated diamond powder in the high-pressure high-temperature treatments reported in Examples 12 and 13. In this regard, Zhou explains (Br. para. bridging 5-6; Spec. 2, ll. 3-14) that due to the “self-stop” process elucidated by Ekimov, the “infiltration” effect used by Ringwood would not have yielded the uniform density required by the claimed process. The Examiner has not come forward with any credible basis to doubt the accuracy of this analysis. In conclusion, the weight of the evidence of record is that ball milling merely to mix diamond and silicon powders is not sufficient to transform ordinary (polycrystalline) silicon to amorphous silicon sufficiently to yield the required product. Moreover, the Examiner has not come forward with any credible evidence supporting a reason to use amorphous silicon powder in place of the silicon powder used by Ringwood. On these facts, the legal conclusion of obviousness cannot stand. C. Order We REVERSE the rejection of the claim under 35 U.S.C. § 103(a) in view of the combined teachings of Ringwood and Kosuzu. REVERSED Appeal 2010-003634 Application 11/444,649 6 sld LOS ALAMOS NATIONAL SECURITY, LLC LOS ALAMOS NATIONAL LABORATORY PPO. BOX 1663, LC/IP, MS A187 LOS ALAMOS NM 87545