Chengsong Zhang

Surface Modification of C17200 Copper-Beryllium Alloy by Plasma Nitriding of Cu-Ti Gradient Film

In the present work, a copper-titanium film of gradient composition was firstly fabricated by the dual magnetron sputtering through power control and plasma nitriding of the film was then conducted to modify C17200 Cu alloy. The results showed that the prepared gradient Cu-Ti film by magnetron sputtering was amorphous. After plasma nitriding at 650xa0°C, crystalline Cu-Ti intermetallics appeared in the multi-phase coating, including CuTi2, Cu3Ti, Cu3Ti2 and CuTi. Moreover, even though the plasma nitriding duration of the gradient Cu-Ti film was only 0.5xa0h, the mechanical properties of the modified Cu surface were obviously improved, with the surface hardness enhanced to be 417 HV0.01, the wear rate to be 0.32xa0×xa010−14xa0m3/Nm and the friction coefficient to be 0.075 at the load of 10xa0N, which are all more excellent than the C17200 Cu alloy. In addition, the wear mechanism also changed from adhesion wear for C17200 Cu substrate to abrasive wear for the modified surface.

Failure Analysis of Insulator Iron Cap in Low Stress State

The safe and stable operations of insulator components create an important issue, with massive constructions of high-voltage direct current (HVDC) projects. However, the service life of the insulator iron cap directly depends on the production process. Therefore, it is necessary to examine the quality of the products and clarify the causes of failure. Under equivalent conditions, the insulator iron cap, made of nodular graphite cast iron, failed when the load value reached 1929xa0kN by calculation, rather than 278xa0kN in this loading test. In this investigation, some of the defects were due to improper heat treatment process. When present, these defects eventually lead to fracture. The results of the research for the process design of insulator iron cap are available.

Crystallographic Texture Evolution of γ′-Fe4N and Its Influences on Tribological Property of Nitrided Steel

The crystallographic texture of γ′-Fe4N in compound layer and its influences on the tribological properties of nitrided steel 38CrMoAl are investigated in the study. The preferred orientation of (200)γ′ is produced by low-temperature nitriding in atmosphere with low nitrogen–hydrogen ratio and increases with the nitriding time. The preferred orientation of (220)γ′ appears after 72xa0h cyclic nitriding. The orientation relationships (0001)ε//(101)α′ and [110]ε//[111]α′, (111)γ′//(0001)ε and

Preparation and characterization of ultra-refined expanded martensite α′N

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Surface Martensite Strengthening of Ultra-fine Porous Iron

011γ′//12¯10ε, (200)γ′//(110)α′ and [011]γ′//[111]α′, as well as

Fabrication and corrosion resistance of super-thick compound layer by austenitic gas oxynitrocarburizing

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