Sintering ceramics have been widely used in industries which require electrical and mechanical properties. Thermal sprayed ceramics coatings are also applied for the industries, however the coating which has micron size pores are limited their applications due to inferior electrical and mechanical properties compared with sintering bulk. To expand thermal sprayed ceramics coating applications, dense coatings prepared by suspension plasma spraying are widely studied. Dense Al 2 O 3 coatings are applicable to fabricating equipment for electronics devices, such as ESC. There are no reports regarding electric properties of plasma sprayed dense Al 2 O 3 coating with different spray conditions. In this study to achieve a electric properties of dense Al 2 O 3 coating, spray parameters such as plasma power, gas flow rate and spray distance are investigated. Suspension materials prepared with three microns Al 2 O 3 powder are sprayed by high power suspension plasma spraying system. Spray conditions, plasma power, gas flow rate, and stand-off distance affect the coating density, crystal phase, and mechanical and electrical properties. Mechanism of coating formation by plasma spraying with fine powder suspensions will be discussed based on the findings. Al 2 O 3 coatings obtained by the plasma spraying is applied for application to application utilizing the electrical insulation properties of such electronics devise manufacturing equipment components is proceeding.

Metal and polymer additive manufacturing is advancing on several applications. On the other hand, materials cermet such as WC/Co for functional structure molding by additive manufacturing are under studying. There are few reports for WC cemented carbide additive manufacturing process by forming with polymer binder then sintering. This indirect process has difficulties to make high precision functional parts due to shape control during additional sintering process. Direct forming is desired for high precision parts. However, factors and/or mechanism to achieve direct formed functional structure have been unclear in many aspects. In this study, the process conditions of the direct selective laser melting were investigated to achieve dense and hard WC cemented carbide mold parts. The optimization of laser melting conditions for WC/Co agglomerated and sintered powder was examined. In order to forming a dense and high hardness parts, the optimum conditions between powder preparation and laser energy density which related with laser power, scan speed and spot diameter were appeared by this experiments. Moldings more than 1500HV are achieved at low laser energy density. However, some of pores were observed in moldings. In addition, the dense molding could be obtained by high laser energy density. This means optimum dense functional WC cemented carbide molding is available by optimization of the molding condition. It is applicable for growing industries like automotive, aviation and cutting tool.

Application of plasma sprayed ceramic coatings with a high purity of more than 99.9% has been sharply increasing in semiconductor and liquid-crystal-display (LCD) production equipments for dry etching, sputtering and ashing in the last few years. The size of the equipments becomes larger with increasing Si wafer size and the LCD size that promotes the replacement from conventional techniques, such as alumite film and bulk ceramics, to plasma spray coatings, where the high durability against the plasma erosion (anti-plasma erosion resistance) is required. However, as far as we know, no systematic studies on the plasma-erosion properties are reported. In this work, durability of plasma sprayed ceramic coatings against CF 4 /O 2 plasma are investigated by reactive ion etching (RIE) system and are compared to that of the conventional techniques. The erosion mechanism is also discussed through the micro-structural analysis.