片状hBN的制备及摩擦性能研究

Study on Preparation and Tribological Properties of Plate hBN

以CaB2O4作为烧结助剂,采用热压烧结技术制备了片状hBN。通过SEM、XRD和摩擦磨损试验机对hBN块体的显微结构、物相组成和摩擦性能进行了表征。结果表明:在N2气气氛下,烧结温度为2000℃,保温时间为5h时,CaB2O4的加入可以有效的提高hBN的结晶性能。烧结hBN呈片状结构,其粒径约为0.52μm,厚度约为200 nm。hBN块体的摩擦系数和磨损量均随着温度的升高先增大后稍有降低,在600℃时,摩擦系数和磨损量均达到最高,其空气和水蒸气气氛下的摩擦系数分别为0.6和0.25磨损量分别为9.1 mg和4.9 mg。在整个测试温度范围内,水蒸气气氛下的摩擦系数和磨损量均比空气气氛下低,这主要是因为:室温下,水蒸汽在hBN与摩擦副的摩擦表面形成一层水膜;高温下,hBN可以与水蒸汽发生反应,生成H3BO3。

The plate hBN was prepared by hot pressed sintering using CaB_2O_4 as an additive.The microstructure,phase analysis and tribological properties of the hBN were studied by SEM,XRD and hightemperature tribometer.The results show that the CaB_2O_4 can effectively promote crystal growth of hBN at2000 ℃ for 5 h in N_2 ambience.The sintered hBN has a plate-like shape and the grain sizes of hBN are 0.5-2μm in diameter,200 nm in thinkness.The friction coefficient and abrasion loss increase and the wear rate of the hBN increases firstly and then decreases with the increase of temperature.The highest values are observed at 600 ℃ under atmosphere ambience and water vapor ambience,and the friction coefficient are about 0.6 and 0.25,the abrasion loss are about 9.1 mg and 4.9 mg,respectively.The friction coefficient and abrasion loss under water vapor ambience,friction coefficients of the sintered hBN are much lower than those under atmosphere ambience which are attributed to the formation of the water film at low temperature and the hBN can react with water vapor to form H_3BO_3 at high temperature.