Microstructure and wear properties of Ni/TiB2-TiC composites prepared by spark plasma sintering
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摘要: 采用放电等离子烧结技术，以Ni、Ti、B4C混合粉末为原料制备Ni/TiB2-TiC复合材料，分析了Ni含量对复合材料的物相组成、组织结构、硬度和耐磨性的影响。结果表明：Ni/TiB2-TiC复合材料主要物相为γ-Ni、TiB2和TiC，其中TiB2呈矩形条状和多边形状，TiC则呈现不规则块状；随着原始粉末中Ni含量的增加，TiB2和TiC陶瓷相尺寸减小，其在Ni粘结相中的分布呈现出均匀化的趋势，复合材料更加致密。Ni含量显著影响Ni/TiB2-TiC复合材料的耐磨性和磨损机制，Ni含量较低时（20wt%和30wt%），复合材料摩擦系数（COF）较大且存在明显的波动，出现严重的疲劳磨损；随着Ni量的增加（40wt%），材料的COF降低且趋于平稳，表现为微切削磨损；当Ni含量持续增加时（50wt%），由于局部Ni的聚集导致粘着磨损产生，COF有所上升，耐磨性反而下降。Abstract: Ni/TiB2-TiC composites were fabricated by spark plasma sintering using Ni, Ti and B4C powder mixture as precursor. Effects of Ni content on phase composition, microstructure, microhardness and wear resistance of composites were analyzed. The results show that the mainly phases of Ni/TiB2-TiC composites are γ-Ni, TiB2 and TiC. TiB2 phase presents rectangle strip and polygon shape, while TiC phase is irregular patch shape. With the increase of Ni content, the size of TiB2 and TiC ceramics decrease gradually. Additionally, TiB2 and TiC homogeneously disperse in the Ni binder phase, and the denser composites are obtained. Wear properties and mechanisms are influenced significantly by Ni content. When Ni content is low(20wt% and 30wt%), severe delaminate occurs with high and fluctuant coefficient of friction(COF). Micro-cutting wear appears with lower and smoother COF with the increase of Ni content(40wt%). However, when the Ni content continues to increase(50wt%), the adhesive wear results in poorer wear resisitance and higher COF due to the aggregation of Ni.
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Keywords:
- spark plasma sintering /
- TiB2-TiC /
- composite /
- microstructure /
- wear resistance
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