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Effect of grinding conditions on the friction and wear performance of Ni based singlecrystal superalloy

Xu Yunchao, Gong Yadong, Zhang Weiqiang, Wen Xuelong, Xin Bo, Zhang Huan

Archives of Civil and Mechanical Engineering

2022

Vol. 22, no. 2

art. no. e102, 1--16

In this work, four types of surfaces were prepared as follows: untreated one, dry grinding (DG), wet grinding (WG) and minimum quantity lubrication grinding (MQLG) for Ni-based single crystal superalloy. The effects of grinding conditions on the surface roughness and microstructure evolution were studied. Dry sliding tests of ground surfaces were carried out at room temperature. Through the quantitative characterization of the wear rate, the area, width and depth of the worn profiles, the friction and wear mechanism of superalloy prepared by different grinding conditions were analyzed. The results show that the MQLG surface with low surface roughness and work hardening behavior has the best wear resistance. The element transfer behavior from the GCr15 ball to the worn surface was detected by EDS analysis. The wear type is mainly abrasive wear, accompanied by slight adhesive wear and oxidation wear. It is shown that high-quality surface with nanocrystalline and high density dislocation structure produced by MQLG improves the tribological properties of superalloy, which provide theoretical guidance for the surface machining of single crystal blade to reduce fretting wear.

Changes of physical properties of thermal damaged sandstone with time lapse

Wang Zuoquan, Zhang Weiqiang, Shi Zhoujian, Zhang Shaoteng

Acta Geophysica

2022

Vol. 70, no 3

1193--1202

Understanding the change of physical properties of thermal damaged rock with time lapse in high temperature engineering plays an important role in the prediction of engineering life and the prevention of engineering disasters. In order to study the effect of time lapse on the physical properties of heat damaged sandstone, the sandstone was heated to the target temperature and cooled, and its resistivity, Leeb hardness, volume and mass were measured. The values of these parameters should be measured again after placing the thermally damaged sandstone for 3, 6 and 9 months. The results show that, after being placed for 3 months, the quality of heat damaged sandstone increased at all test temperatures. At 200 °C, 400 °C, 600 °C and 900 °C, the resistivity of heat damaged sandstone decreases, and there is no obvious change in Leeb hardness and volume. At 800 °C, the resistivity of thermally damaged sandstone increases, the Leeb hardness decreases and the volume increases. After being placed for 6 months, the resistivity, Leeb hardness and volume of thermally damaged sandstone did not change at all test temperatures, but the mass of thermally damaged sandstone increased at 800 °C and 900 °C. After being placed for 9 months, the resistivity, Leeb hardness, volume and mass have no obvious change at all test temperatures.