분말소재 특성에 따른 고속화염용사 WC-12Co 코팅층의 미세조직 및 침식 저항성 |
강소영1, 백경호1, 윤상훈2, 김형준2 |
1충남대학교 신소재공학과 2포항산업과학연구원 |
Effects of Feedstock Powder Characteristics on the Microstructural Features and Erosion Resistance of WC-12Co Coatings |
So-Yeong Kang1, Kyeong-Ho Baik1, Sang-Hoon Yoon2, Hyung-Jun Kim2 |
1Department of Materials Science and Engineering, Chungnam National University, Daejeon 34134, Republic of Korea 2Research Institute of Industial Science and Technology, Pohang 37673, Republic of Korea |
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Received: 11 October 2017; Accepted: 14 November 2017. Published online: 5 February 2018. |
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ABSTRACT |
WC-Co coatings manufactured by high velocity oxy-fuel (HVOF) spraying have a superior hardness and wear resistance. In this study, HVOF-sprayed WC-12Co coatings from three different feedstock powders were evaluated in terms of microstructural features, carbide decomposition and erosion resistance. The fused-crushed and the sintered-crushed WC-12Co powders had an angular shape, a dense internal structure and a high apparent density, whereas the agglomerated-sintered powder was found to have a spherical morphology with a porous internal structure and a relatively low apparent density. These differences in powder characteristics significantly affected porosity, carbide decomposition, microhardness and erosion resistance in the WC-Co coating. The fused-crushed coating contained a large amount of intersplat pores and a low fraction of carbide, resulting in the lowest microhardness. The erosion wear rate of the fused-crushed coating increased sharply with increasing impact angle, due to the brittle damage mechanism. The agglomerated-sintered coatings had a low porosity and a high microhardness, and consequently exhibited superior erosion wear resistance with no dependency on impact angle. |
Keywords:
WC-Co, HVOF coating, powder processing, porosity, erosion |
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