1999 / Solid Freeform Fabrication Proceedings
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Author Lianchao Sun, James E. Crocker, Leon L. Shaw, Harris L. Marcus, The University of Connecticut at Storrs
Source Solid Freeform Fabrication Proceedings, 1999, pp 479-486
Abstract Silicon carbide has long been recognized as an ideal material for applications where superior attributes such as stiffness and hardness, strength at elevated temperatures, high thermal conductivity, low coefficient of thermal expansion and resistance to corrosion, oxidation, wear and abrasion are of primary value. Silicon carbide or its composites for structural applications are usually fabricated using hot pressing (H-P), sintering, reaction sintering, pressureless sintering, or hot isostatic pressing (HIPing). All these belong to powder metallurgy approach. To reduce processing temperature and/or processing time, the second phase is almost widely strategically used in above techniques. In other words, the "impurity" materials, at least two phases, act to compromise the true performance of the silicon carbide. For example, some reaction bonded SiC contains as much as 40% second phase. This, of course, is not a case in the electronic applications of SiC where high purity SiC is required. It is also obvious that using powder metallurgy is difficult to produce SiC parts with a complex shape because of its high hardness and low toughness. Selective area laser deposition (SALD) is a unique technique for fabricating complex ceramic shapes, tailoring functionally graded structures and embedding in-situ sensors into ceramic parts. In general, high deposition rate is desired. For the case of fabricating in-situ sensors, the chemical composition must also be controlled. Proper shapes and deposition rate using tetramethylsilane (TMS) precursor to deposit SiC has been demonstrated in previous studies. However, carbon contamination has been found to be a potential obstacle for the further application of this precursor in sensor-related fabrication. It has been suggested using the thermodynamic calculation that hydrogen has significant effect on the composition of SiC deposits. In this study, therefore, the effect of hydrogen on the SALD SiC will be experimentally evaluated. (Auth abstract) [References: 12]
Solid Freeform Fabrication Proceedings can be obtained from: The Solid Freeform Fabrication Symposium
or contact:
The University of Texas at Austin
Laboratory for Freeform Fabrication / Texas Materials Institute
Mechanical Engineering Dept.
c/o The Solid Freeform Fabrication Symposium
MC C2200
Austin, TX 78712-1063 USA
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