Development of new tool ceramic materials combining binder-less WC and silicon nitride and its sintering mechanisms

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14841
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Material processing/Microstructural control engineering
• Research Institution: Akita University
• Principal Investigator: Nino Akihiro 秋田大学, 理工学研究科, 准教授 (80451649)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 通電加圧焼結 / 炭化タングステン / 窒化ケイ素 / 複合セラミックス / 高い硬さ / 高いヤング率 / 高い破壊靭性値

Outline of Final Research Achievements

Binder-less Si3N4-WC composite ceramics containing sintering aids were densely sintered above 1500℃ with a resistance-heated hot-pressing machine. The α-Si3N4, β-SiAlON and WC phases were detected in the ceramics containing WC. The proportion of α phase was decreased with increasing sintering temperature. The addition of WC was effective in inhibiting α to β phase transition. Young's modulus, hardness and fracture toughness of Si3N4-WC composite ceramics were increased with increasing the WC amount.
Binder-less WC-Si3N4 composite ceramics without sintering aids were densely sintered under 0-30 mol% Si3N4 at 1650℃. The Vickers hardness and electrical resistivity of the binder-less WC-Si3N4 composite ceramics were closed to those of pure WC ceramics. The binder-less WC-Si3N4 composite ceramics consolidated without sintering aids and had superior mechanical properties.

Free Research Field

材料工学

Academic Significance and Societal Importance of the Research Achievements

金属バインダーを用いない、バインダーレスの機械的性質における優位性を生かしながら、炭化物であるWCと窒化物であるSi3N4を複合化することにより新たな難削材加工用工具材料を開発の指針が得られる。WCとSi3N4を複合化することにより焼結性が改善され、セラミックス製造時の装置の損耗や投入電力のコストを低減させるとともに、これら複合セラミックス合成および要求される機械的性質に対する組織制御指針を与える。