【摘要】：陶瓷結合劑cBN (立方氮化硼)磨具具有磨削力強,高速加工時不燒傷工件,可修整且耐用等優(yōu)點,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屬及其合金方面具有無與倫比的優(yōu)勢。因此,研究高性能cBN磨具用陶瓷結合劑具有重要的意義。本文以Si02-Al203-B203-R20-RO系玻璃為基礎,利用紅外光譜分析、X射線衍射分析、掃描電子顯微鏡、熱膨脹系數(shù)和力學性能測試等手段研究了(Na20+Li20)與Si02的摩爾比(堿硅比)對陶瓷結合劑結構與性能的影響規(guī)律。在此基礎上,研究了外加MgF2、β-鋰輝石或AlN對基礎陶瓷結合劑力學性能、熱膨脹系數(shù)、物相組成、微觀結構等的影響規(guī)律。最后,探討了陶瓷結合劑堿硅比、cBN粒度對cBN磨具氣孔率、顯微結構、抗彎強度和磨削性能的影響。研究結果顯示,陶瓷結合劑配方組成中的堿硅比對其熔融程度、[Si04]、[B03]和[B04]等基團的結合、玻璃相含量等均有影響;陶瓷結合劑的耐火度隨著堿硅比的增大而降低。堿硅比為0.12時,陶瓷結合劑在680 ℃燒結后的抗彎強度最高,達到了 152 MPa。隨著堿硅比的增大,陶瓷結合劑燒結體的最佳燒結溫度及其抗彎強度逐漸降低;顯微硬度總體上呈逐漸降低的趨勢,熱膨脹系數(shù)呈逐漸上升的趨勢,但會受燒結體的物相組成和顯微結構影響。陶瓷結合劑燒結體的熱膨脹系數(shù)隨AlN添加量的增大而逐步降低,但添加β-鋰輝石、MgF2時卻影響不大。添加AlN和β-鋰輝石使燒結體的抗彎強度降低,而添加MgF2卻使其有所提高,當MgF2含量為8wt%時,抗彎強度達到最大值153 MPa,比未添加時提高了 10%。陶瓷結合劑的堿硅比對cBN磨具的抗彎強度、氣孔率和磨削性能影響較大。堿硅比由0.12逐步增大到0.16、0.20時,cBN磨具的最高抗彎強度和氣孔率逐步降低,分別為77、70、60 MPa和19.78、15.94、12.14%;堿硅比為0.16時,cBN磨具的磨削性能最好。cBN磨具的抗彎強度和磨削性能隨著所用cBN磨料的粒度增大而變差。添加8 wt%MgF2對陶瓷結合劑(堿硅比0.12)改性后,所制cBN磨具的氣孔率升高,抗彎強度略有降低,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，

本文編號：2256736