High-purity oxide ceramic powders of alumina (Al 2 O 3 ) and yttria (Y 2 O 3 ) have been developed to apply to semiconductor and flat-panel-display (FPD) production equipment. The ceramic coatings on the inside chamber wall of the equipment are required to have high erosion resistance against CFx plasma in dry etching process for microfabrications of the devices. It is found that the yttria coating formed from agglomerated-and-sintered powder consisting of large primary particles has smoother eroded surface with high erosion resistance. Considering the particle deposition on the devices, this coating will be effective in decreasing generation of large-sized particles, which easily deposit on the devices. Electric insulating properties of the coatings are also investigated to apply to electrostatic chuck. Electric breakdown voltage of yttria coatings is comparable to that of alumina coatings. Smaller powder is effective for improving the electric properties, and the influence of coating purity is lower than that of the powder size.
Recently, the practical research and development of SB latex for a cement modifier have taken place and the cement mortars so modified are used in the field of building or civil engineering. The physical and chemical properties of SB latex-modified mortars have already been reported, but the effects of various polymerization conditions for latex synthesis on properties of SB latex-modified mortars have hardly been noticed. The authors discuss the effects of polymerization conditions, in particular, styrene/butadiene monomer ratio on physical properties of SB latex-modified mortar and conclude that the physical properties such as strength, drying shrinkage, adhesion, abrasion and shock resistance, etc., of SB latex-modified mortars are affected more intensely by the variation of bound styrene contents than by the rubber-cement ratios.
In this paper, the microstructure formation process of WC cemented carbide manufactured by Laser Powder Bed Fusion (LPBF) was investigated with WC/25 wt%Co agglomerated and sintered powder. The internal structure of the as-built cemented carbide specimen was categorized into two regions. The first region included many pores and a unique microstructure which was not observed from the samples fabricated with conventional manufacturing methods. In this region, W 2 C and W 3 Co 3 C were formed due to a WC decomposition and an evaporation of graphite and Co during laser irradiation. On the other hand, the second region showed the similar microstructure to the conventional method. The microstructure of the first region revealed that the powder was completely melted during a laser scanning process. The precipitation process of W 2 C, W 3 Co 3 C, and Graphite phase was considered with calculated liquidus projection of a C-CoW ternary phase diagram.
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