Fabrication of WC–Co cermets by laser engineered net shaping

Abstract The Laser Engineered Net Shaping (LENS ® ) technology is an extension of rapid prototyping technologies into the direct fabrication of metal parts. Bulk dense tungsten carbide–cobalt (WC–Co) cermets were produced without any molds using the LENS ® technology, starting from granules consisting of nanostructured WC crystallites in a Co matrix. Thermal behavior of the LENS ® process, shape change and coarsening of WC crystallites were investigated in this work to study the mechanisms of microstructural evolution of the cermets. Microstructures with alternating layers were observed, which is relevant to the thermal behavior of the LENS ® process. Variations in hardness result from the change in cooling rate along the specimen height.

[1]  M. L. Griffith,et al.  Solidification in direct metal deposition by LENS processing , 2001 .

[2]  W. Schubert,et al.  On the formation of very large WC crystals during sintering of ultrafine WC–Co alloys , 2002 .

[3]  K. Hartwig,et al.  Consolidation of advanced WC–Co powders , 2000 .

[4]  P. Becher.  Microstructural design of toughened ceramics , 1991 .

[5]  Ronald W. Smith,et al.  Thermal spraying I: Powder consolidation—From coating to forming , 1995 .

[6]  J. Intrater.  A review of “Phase Equilibria Diagrams, Volume XII” Edited by A. McHale and R. Roth To obtain contact: American Ceramic Society 735 Ceramic Place Westerville, OH 43081 , 1998 .

[7]  A. Mchale,et al.  Phase equilibria diagrams : phase diagrams for ceramists , 1992 .

[8]  G. K. Lewis,et al.  Practical considerations and capabilities for laser assisted direct metal deposition , 2000 .

[9]  Shinhoo Kang,et al.  Sintering of nano-sized WC–Co powders produced by a gas reduction–carburization process , 2006 .

[10]  V. Sobolev,et al.  Dynamic processes during high velocity oxyfuel spraying , 1996 .

[11]  G. Ji,et al.  Nanostructured WC?Co alloy prepared by mechanical alloying , 1996 .

[12]  F. L. Zhang,et al.  Nanostructured WC/Co composite powder prepared by high energy ball milling , 2003 .

[13]  Z. Fang,et al.  Study of nanostructured WC-Co composites , 1995 .

[14]  L. E. Mccandlish,et al.  Production capability and powder processing methods for nanostructured WC-Co powder , 1997 .

[15]  John N. DuPont,et al.  Fabrication of functionally graded TiC/Ti composites by Laser Engineered Net Shaping , 2003 .

[16]  S. Luyckx,et al.  Fine Grained WC–VC–Co Hardmetal , 1996 .

[17]  T. Xiao,et al.  Deposition and characterization of nanostructured WC–Co coating , 2001 .

[18]  J. Schoenung,et al.  A review on nanostructured WC–Co coatings , 2002 .

[19]  B. Kear,et al.  Chemical processing and properties of nanostructured WC-Co materials , 1993 .

[20]  B. Kear,et al.  Processing and properties of nanostructured WC-Co , 1992 .