不同无机铵盐对陶瓷结合剂CBN砂轮造孔的应用研究

分别研究了无机铵盐NH4F、NH4Cl、（NH4）2SO4和NH4HCO3的不同添加量对低温陶瓷结合剂CBN砂轮造孔的影响，采用气孔率、抗折强度以及试样SEM断口形貌对造孔效果进行了评价。结果表明：NH4Cl使砂轮开裂，不能作为低温陶瓷结合剂CBN造孔剂。NH4F造孔效果不明显，不适合造孔。（NH4）2SO4造孔剂的质量分数应控制在5％以内，质量分数达到5％时，砂轮孔隙率为36．14％，抗折强度为29．03MPa，气孔皆为小孔，气孔可调性差。NH。HCO，造孔剂质量分数应控制在15％以内，质量分数为5％时，砂轮孔隙率为34．19％，抗折强度为40．32MPa；质量分数增加到15％时，孔隙率达到42．5％，抗折强度为29．16MPa，且大孔径气孔比例随质量分数的提高而提高，气孔可调性好。

Pore-forming effect of different inorganic ammonium salts applied on vitrified bond CBN wheels

Four kinds of inorganic ammonium salts such as： NH4F, NH4Cl, （NH4） 2SO4 and NH4HCO3 were added on low- temperature sintering vitrified bond CBN wheels at different mass percentages. Their poreforming effects were evaluated by testing their porosity, bending strength and bending fractures observed using SEM. The experimental results show that NH4Cl is not an ideal pore-forming agent for it causes the wheel cracking; the pore-forming effect of NH4F is not obvious, so it is not a suitable alternative. The mass percentage of （NH4）2SO4 should be controlled to 〈5% , when the mass percentage reaches 5% , the porosity of sample is 36. 14% and its bending strength is 29.03 MPa; the pore size is small and can be poorly adjusted. The mass percentage of NH4HCO3 should be less than 15% ; when the mass percentage is 5% , its porosity is 34. 19% and the bending strength is 40. 32 MPa; while the mass percentage reaches 15% , its porosity can reach 42.5% and its bending strength is 29. 16 MPa; and within this amount the proportion of big pore increases as the addition amount increases and the pore sizes are well adjusted.