微弧等离子堆焊沉积Ni/硅藻土高温封严涂层的腐蚀磨损特性

Corrosive-Wearing Resistance Behavior of Ni/Diatomite Abradable Seal Coatings Produced by Micro-Arc Plasma Welding

高温封严涂层在腐蚀环境中的摩擦磨损是影响其服役寿命的主要问题之一。为此,研究了微弧等离子堆焊沉积Ni/硅藻土封严涂层的工艺规律与腐蚀摩擦学性能。对粉末和涂层的基本结构的表征显示:涂层呈现堆叠结构,含有大量孔隙,涂层主要由Ni,SiO_2和少量NiO组成。涂层的内聚强度平均达到8.78MPa,在拉伸应力作用下表现为以扁平化粒子边缘为主,沿着孔隙率方向应力集中的脆性断裂,以及在应力集中部位导致硅藻土粒子内部的穿晶断裂。当堆焊电流为40A时,微弧等离子堆焊制备的Ni/硅藻土封严涂层在盐环境和酸环境的摩擦系数和磨损率分别达到0.524,16.354wt.‰和0.5099,17.317wt.‰。Ni/硅藻土可磨耗封严涂层在酸性环境的腐蚀能力较低,其平衡电位达到-708m V。

The wear property at corrosion environment is one of the main problems in the service life cycle of high temperature sealing coating. The micro-structure and corrosive-wearing resistance properties of Ni/diatomite coatings deposited by micro-arc plasma welding was reported. It shows that the coatings with a layer structure contain a large number of pores,which are mainly composed of Ni,SiO2 and a small amount of NiO. The mean bonding strength of coatings is about 8.78 MPa. Under the tensile stress,the fracture mechanism takes on the cohesive strength,where the stress were focused on the edge of flattened particle,the direction of the porosity of the brittle fracture,and diatomite particles within the trans-granular fracture. In the salt and acidic environment,when the welding current is 40 A,the friction coefficient and wear rate of Ni/ diatomite abradable coatings produced by micro-arc plasma welding were stable relatively,and reached 0.524,16.354 wt.‰ and 0.5099,17.317 wt.‰,respectively. At acidic solution environment,the corrosion resistance performance of Ni/ diatomite abradable coatings is lower than that in the salt solution,and the equilibrium potential is-708 m V.