氮化硅陶瓷球研磨过程中微磨料磨损形式的转变

Wear mode transition in micro-abrasive of silicon nitride ceramic balls

为探究氮化硅陶瓷球研磨过程中的磨料磨损,在Rtec MFT5000摩擦试验机上,用不同载荷及不同浓度的金刚石磨料对其进行磨损试验,用VHX-1000超景深显微镜和S-4800扫描电镜观察磨损表面,确定其磨损形式,绘制摩擦因数的拟合关系曲线图。考虑部分实际工况,建立二、三体磨损模型。结果表明:磨料浓度对磨损形式转变的影响大于载荷。磨料质量分数为5%时出现明显沟槽;质量分数为20%时沟槽较浅;质量分数为35%时几乎无沟槽。计算确定磨损形式的转变临界值D/h≈1.6,当D/h<1.6时,二体磨损逐渐转变为三体磨损,随磨料浓度增大,材料表面磨损程度降低,D/h接近1,在磨料质量分数超过35%时,磨损形式几乎全部转变为三体磨损,试验初始摩擦因数较高随后降低并趋于平稳,不同磨料浓度造成摩擦因数差值较大,不同载荷造成摩擦因数差值较小。减小载荷或增大磨料浓度使D/h减小,能适当降低磨损程度,摩擦因数主要与滚动、滑动磨粒数量有关,滑动磨粒数量越多摩擦因数越大,摩擦因数波动随载荷增大而减小。

The work aims to explore the role of wear forms in the grinding process of silicon nitride ceramic balls. On the Rtec MFT5000 friction testing machine,different loads and different concentrations of diamond abrasives were used to perform wear experiments on silicon nitride ceramic balls. The wear surface was observed by VHX-1000 ultra-depth-of-field microscope and S-4800 scanning electron microscope to determine the wear form,and draw a curve fitting relationship diagram of friction coefficient. Considering some actual working conditions,established two-body and three-body wear models that fit more closely to reality. The abrasive concentration has a more pronounced influence on the change of wear form than the load. Obvious grooves appear when the abrasive concentration is 5%,the groove is shallow when the abrasive concentration is 20%,and there is almost no groove when the abrasive concentration is 35%. The critical value of the wear form transition D/h was calculated to be about 1.6. When D/h is less than 1.6,two-body wear from gradually transforms into three-body wear form. With an increase in the abrasive concentration,the severity of the wear on the surface of the material gradually decreases,and D/h gradually approaches 1,when the abrasive concentration reaches 35%,the form of wear is transformed into three-body wear. The friction coefficient decreases gradually and tends to be stable. The friction coefficient changes significantly with abrasive concentration but varies slightly with load. Increasing the abrasive concentration or reducing the load can appropriately reduce the severity of wear. The fluctuation of the friction coefficient is mainly related to the number of rolling abrasive particles and sliding abrasive particles. The more the number of sliding abrasive particles,the greater the friction coefficient. The friction coefficient fluctuation decreases as the load increases.