Fabrication and Mechanical Properties of TiB_2-B_4C Composite Ceramics by Spark Plasma Sintering Method

放电等离子烧结法制备TiB_2-B_4C复合陶瓷及其力学性能

• 批准号: 13650769
• 负责人: MORIYAMA Minoru
• 金额: $ 0.64万
• 依托单位: Nagano National College of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650769/
• 关键词: TiB_2-B_4C composite ceramics; Spark plasma sintering; Mold material; High strength; High fracture toughness; High electrical conductivity; Electrical discharge machining; Additives; TiB_2-B_4C系複合セラミックス; 金型素材; 機械的特性; 電気的特性; 加工電力; 表面粗さ; 硼化物系複

To develop the mold material made of hard ceramics in which the electrical discharge machining (EDM) is possible, the TiB_2-B_4C ceramic composites containing 0 up to 100 mol%B_4C (20mol%steps) were fabricated from a mixture of TiB_2 and B_4C powders by Spark Plasma Sintering(SPS) method that was possible to product efficiently. SPS condition was 1680-1750°C for 720s under a pressure of 40.0 MPa in a vacuum, and the examination of the composite revealed mechanical and electrical properties and EDM characteristics as a function of compositional change from TiB_2 to B_4C. Optimum additive to improve mechanical properties was also investigated for the composite with the content of 40mol%B_4C.(1)The derived TiB_2-B_4C composite containing 40-60 mol%B_4C with no additives had following high properties. A relative density could be attained more than 96%, Vickers hardness 30 GPa, flexural strength 730 MPa, Young's modulus 450 GPa, fracture toughness (Kic) 5.4 MPa・m^<1/2> or more, respectively. The mean surface roughness (Ra) was below 25 nm, and electrical conductivity in the range of 0.25-1.32 MS・m^<->1.(2)The composites presented high mechanical properties compared with those for TiB_2 or B_4C single phase, and possesed the comparable properties manufactured by hot-pressing method at 1950°C with the same composition.(3)The composites were machinable by electric discharge with high-speed using the conditions for steel. Hence, the composite was useful for ceramic mold material. The mechanical properties after processing of EDM were about 70% of those bofore.(4)AIN was the optimum additive to improve the mechanical properties of TiB_2-B_4C ceramic composite. AINpromoted especially the Kic up to 8.OMPa・m^<1/2>.By adopting the composite ceramics as mold materials, it is presumed that the long-term life of mold, improvement of heat-resistant and corrosion-resistant are attained.

为了开发可进行放电加工（EDM）的硬质陶瓷模具材料，用TiB_2和B_4C粉末的混合物制备了含有0至100 mol%B_4C（20mol%级）的TiB_2-B_4C陶瓷复合材料通过火花等离子烧结（SPS）方法，可以有效生产SPS条件为1680-1750°C。在真空中、在 40.0 MPa 的压力下进行 720 秒的测试，对复合材料进行了测试，结果显示机械性能、电性能以及 EDM 特性随成分从 TiB_2 变为 B_4C 的变化而变化，同时还研究了复合材料的机械性能的最佳添加剂。 40mol%B_4C含量。(1)所得含40-60mol%B_4C且不含任何添加剂的TiB_2-B_4C复合材料具有以下高相对密度可以达到96％以上，维氏硬度为30GPa，弯曲强度为730MPa，杨氏模量为450GPa，断裂韧性(Kic)为5.4MPa·m^<1/2>以上。表面粗糙度（Ra）低于25 nm，电导率在0.25-1.32范围内MS·m^<->1。(2)与TiB_2或B_4C单相相比，复合材料表现出较高的力学性能，并且具有与相同成分在1950℃热压法制备的材料相当的性能。(3 )该复合材料可在钢的条件下进行高速放电加工，因此，该复合材料可用于陶瓷模具材料，电火花加工后的机械性能约为陶瓷模具材料的70%。 (4)AIN是提高TiB_2-B_4C复合陶瓷力学性能的最佳添加剂,尤其是Kic提高到8.OMPa·m^<1/2>。采用复合陶瓷作为模具材料,提高了复合陶瓷的力学性能。推测可实现模具的长寿命化、耐热性、耐腐蚀性的提高。