Due to the mismatching in the coefficients of thermal expansion between the surperhard particles and the bond, residual stresses that affects negatively the final cutting performance of the tools often occur at the interfaces during sintering. In this paper, comparison experiments of dimond/vitrified bond composites prepared with traditional and the developed low-point and high strength nano-vitrified bond were carried out to study the effects of grit size and the bond type on the stresses using bending strength test and SEM methods. Industrial application results of coarse diamond tools with the high-strength nano-vitrified bond show that the interfacial stress between diamond and matirx increased and microcracks formed at the interface with the increase of diamond grit size, resulting in decreasing the bending strength. The composites with nano-vitrified bond lead to a lower stress value and consequently had a higher bending strength than those with the traditional bond. The successful industrial applications of the nano-vitrified bonded coarse diamond tools proved that the nano-vitrifed bond had a significant reduction in the stress and remarkable increase in the strength and durability of the tools.%在超硬工具的烧结过程中,由于结合剂与磨料之间的热膨胀系数的不同,容易在其界面处产生应力,进而降低工具的使用性能.本文通过同一成分的普通陶瓷结合剂与纳米陶瓷结合剂的对比实验,运用抗折强度实验、SEM 等实验手段研究了粒度及结合剂类型对界面应力的影响.并将高强纳米陶瓷结合剂粗粒度超硬工具应用于工业化.结果表明:随着超硬磨粒颗粒变粗,结合剂-磨料界面积累的应力变大,界面产生微裂纹,超硬工具的强度降低;纳米陶瓷结合剂比传统非纳米陶瓷结合剂具有更强的承受抗拉应力的能力,同一制备条件下的试样,由普通结合剂制取的试样更易于产生微裂纹,进而抗折强度值低.工业化应用的实践证明:采用纳米材料作为结合剂显著降低了界面应力,大幅度提高了制品强度、韧性和耐磨性,实验结果的稳定性和重现性良好,并成功获得了工业化应用.
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