熔融模拟灰在h-BN基陶瓷涂层表面的粘附特性

Adhesion Properties of Molten Simulated Ash on Surface of h-BN-based Ceramic Coating

针对锅炉燃烧劣质煤过程中存在的结渣问题,采用料浆法在20G钢材表面制备了h-BN基陶瓷涂层,对熔融模拟灰在钢片及涂层表面的接触角、铺展系数、粘附功等参数进行研究,进而分析熔融模拟灰在两种试样表面的粘附特性。结果表明:涂层表面较为致密,且与基材嵌合紧密,涂层附着力等级为0级,耐冲蚀性能较好,不易脱落。熔融模拟灰在涂层表面的接触角较大、粘附功较小。熔融模拟灰在涂层表面铺展系数较小,而且随着温度升高,熔融灰在涂层和钢片表面铺展系数的差值逐渐增大,在倾斜放置的试样表面,涂层和钢片铺展系数差值随着角度的增加而增大。通过对试样片截面的SEM/EDS分析可知,涂层对熔渣具有化学不亲和性,能有效阻止Pb的扩散,表明在钢片表面喷涂涂层能减弱熔融灰的润湿性和结合强度,提高其防结渣性能。

To solve the slagging problems existing in the boiler burning inferior coal,the h-BN-based ceramic coating was prepared on the surface of 20 G steel by a slurry method.The experiments on the contact angle,the spreading coefficient and the adhesion work of the molten simulated ash on the steel sheet and the coating surface were carried out,and the adhesion properties of the molten simulated ash on the surface of two types of samples were analyzed.The results show that the surface of the coating is compact,tightly embedded with the substrate.The coating adhesion class is 0,and the anti-erosion performance is better,without easily falling off.The contact angle of the simulated ash on the surface of the h-BN-based ceramic coating is larger,and the adhesion work is smaller.Melted simulated ash has a smaller spreading coefficient on the surface of the coating.Moreover,with the increase of temperature,the difference between the spreading coefficient of molten ash on the surface of the coating and steel sheet increases.On the surface of the inclined specimen,the difference between the spread coefficient of the coating and the steel sheet increases with the angle increasing.Through the SEM/EDS analysis of the cross section of the melten ash specimen,the coating has the chemical incompatibility of slag,which can effectively prevent the diffusion of Pb.It is indicated that spraying h-BN-based ceramic coating on the surface of 20 G steel can reduce the wettability and bonding strength of the molten ash,and improve its anti-slagging performance.