涂层压入仪的研制及其应用

Indentation tester for coating and its application

报道了涂层压入仪的研制背景、结构原理、主要技术特性及其应用举例,该仪器具有连续加载卸载功能并配有声发射和光学系统,能测量并记录连续的载荷与压入深度关系曲线,能用声发射系统对测试过程中涂层试样的开裂和剥落进行动态监测,并确定对应的载荷,用涂层压入仪作界面压入测得厚涂层与基体界面开裂的临界载荷pw可反映涂层的结合强度;也可正面压入考察薄膜与基体的结合,区分薄膜开裂和剥落并精确测定其对应的载荷值,用加载过程中发生初始剥落的载荷表征膜的结合强度,涂层压入仪还可用于膜韧性、膜和膜,基断裂韧性、离子氮化层脆性等的评价,测定块体材料硬度、塑性功、弹性功、弹塑性比等性能指标。

The investigation background, structure principle, properties and application of a new indentation tester for coating were discuesed. The tester can perform continuously loading and unloading in a range of 0 ～ 1 500 N. Amonitoring system for acoustic emission signal, and optical microscopy was attached. The load vs. indentation depth with acoustic emission signal for cracking or delamination of coating can be plotted. The critical load, P_W, of cracking at the interface between thick thermal sprayed coating and substrate was measured at one tested point by the tester. The P_W can evaluate the adhesion of the coating to the substrate. The tester can be used for the measurement of bonding strength of the film/substrate by surface normal indentation method. It is verified that AE signal by film cracking is different from that of delaminatio.n, so cracking load and delaminating load can be distingnshed. The critial load P_C is associated with the film delaminating during loading and can be used to evaluate the bendingstrength of film/substrate. The tester can be also used to evaluate the toughness of the film, the fracture toughness: of the film and film/substrate, the brittleness of the plasma nitriding laryer etc. The tester can measure the hardness, plastic deformation work, elastic deformation work and elastic/plastic rate of bulk material.