cBN磨具用陶瓷结合剂的研究

发布时间：2018-10-08 12:24

【摘要】：陶瓷结合剂cBN (立方氮化硼)磨具具有磨削力强,高速加工时不烧伤工件,可修整且耐用等优点,是目前理想的高速、高效和高精度的磨削工具,尤其是在加工黑色金属及其合金方面具有无与伦比的优势。因此,研究高性能cBN磨具用陶瓷结合剂具有重要的意义。本文以Si02-Al203-B203-R20-RO系玻璃为基础,利用红外光谱分析、X射线衍射分析、扫描电子显微镜、热膨胀系数和力学性能测试等手段研究了(Na20+Li20)与Si02的摩尔比(碱硅比)对陶瓷结合剂结构与性能的影响规律。在此基础上,研究了外加MgF2、β-锂辉石或AlN对基础陶瓷结合剂力学性能、热膨胀系数、物相组成、微观结构等的影响规律。最后,探讨了陶瓷结合剂碱硅比、cBN粒度对cBN磨具气孔率、显微结构、抗弯强度和磨削性能的影响。研究结果显示,陶瓷结合剂配方组成中的碱硅比对其熔融程度、[Si04]、[B03]和[B04]等基团的结合、玻璃相含量等均有影响;陶瓷结合剂的耐火度随着碱硅比的增大而降低。碱硅比为0.12时,陶瓷结合剂在680 ℃烧结后的抗弯强度最高,达到了 152 MPa。随着碱硅比的增大,陶瓷结合剂烧结体的最佳烧结温度及其抗弯强度逐渐降低;显微硬度总体上呈逐渐降低的趋势,热膨胀系数呈逐渐上升的趋势,但会受烧结体的物相组成和显微结构影响。陶瓷结合剂烧结体的热膨胀系数随AlN添加量的增大而逐步降低,但添加β-锂辉石、MgF2时却影响不大。添加AlN和β-锂辉石使烧结体的抗弯强度降低,而添加MgF2却使其有所提高,当MgF2含量为8wt%时,抗弯强度达到最大值153 MPa,比未添加时提高了 10%。陶瓷结合剂的碱硅比对cBN磨具的抗弯强度、气孔率和磨削性能影响较大。碱硅比由0.12逐步增大到0.16、0.20时,cBN磨具的最高抗弯强度和气孔率逐步降低,分别为77、70、60 MPa和19.78、15.94、12.14%;碱硅比为0.16时,cBN磨具的磨削性能最好。cBN磨具的抗弯强度和磨削性能随着所用cBN磨料的粒度增大而变差。添加8 wt%MgF2对陶瓷结合剂(碱硅比0.12)改性后,所制cBN磨具的气孔率升高,抗弯强度略有降低,磨削性能略有提高。
[Abstract]:Ceramic bond cBN (cubic boron nitride) grinding tool is an ideal high speed, high efficiency and high precision grinding tool, because it has the advantages of high grinding force, no burn workpiece during high speed processing, trimming and durability, etc. Especially in the processing of ferrous metals and their alloys have unparalleled advantages. Therefore, it is of great significance to study ceramic binders for high performance cBN abrasives. In this paper, based on the Si02-Al203-B203-R20-RO glass system, the X-ray diffraction analysis and scanning electron microscope (SEM) are used to analyze the glass. The influence of molar ratio of (Na20 Li20) to Si02 (alkali-silicon ratio) on the structure and properties of ceramic binders was studied by means of thermal expansion coefficient and mechanical properties. On this basis, the effects of MgF2, 尾 -spodumene or AlN on the mechanical properties, thermal expansion coefficient, phase composition and microstructure of the base ceramic bond were studied. Finally, the effects of the size of alkali / silicon ratio CBN on the porosity, microstructure, bending strength and grinding properties of cBN abrasives were discussed. The results show that the ratio of alkali to silicon in the composition of ceramic binder has an effect on the melting degree, the combination of [Si04], [B03] and [B04] and the content of glass phase, and the fire resistance of ceramic binder decreases with the increase of the ratio of alkali to silicon. When the ratio of alkali to silicon is 0.12, the bending strength of ceramic bond sintered at 680 鈩，

本文编号：2256736