Papers by Author: Yi Chao Ding

Abstract: It is difficult to build a strict mathematical model for WEDM due to the complication of the machining process and the nonlinear relation between process parameters and process targets. The neural network is suited to the modeling of complex system, because it has the functions of self-organized, self-learning and associative memory, and properties of distributed parallel type and high robustness. Therefore, this paper attempts to use the RBF neural network for the process modeling of WEDM.

Abstract: A wear resistant TiC-Cr₇C₃ /Fe surface composite was produced by cast technique and in-situ synthesis technique. The microstructure and dry-sliding wear behavior of the surface composite was investigated using scanning electron microscope(SEM), X-ray diffraction(XRD) and MM-200 wear test machine. The results show that the surface composite consists of TiC and Cr₇C₃ as the reinforcing phase, α-Fe and γ-Fe as the matrix. The surface composite has excellent wear-resistance under dry-sliding wear test condition with heavy loads.

Abstract: Vanadium and chromium-carbide particulates reinforced iron matrix surface composite was produced by cast technique and in-situ synthesis technique. The microstructure of the surface composite was studied by scanning electron microscope(SEM) and X-ray diffraction(XRD). The results show that the production of an iron matrix surface composite reinforced by vanadium and chromium-carbide particulates using the process is feasible. Spherical VC particles and strip-chunky Cr7C3 are generated in the surface composite. An excellent metallurgy-bond is observed between the surface composite and the mater-steel.

Abstract: TiC particulates reinforced iron matrix surface composite was produced by cast technique and in-situ synthesis technique. The surface composite was investigated from thermodynamics, microstructure, wear-resistance and oxidation-resistance. The results show TiC particles whose volume fraction is about 40% exhibit fine size in iron matrix on the surface composite. An excellent metallurgy-bond is observed between the surface composite and the gray iron. Fe-TiC surface composite shows good oxidation-resistance at 900°C and great wear-resistance under condition of dry sliding.

Abstract: A new fabrication method for VC-Fe surface cermets by cast-sintering has been developed in the study. SEM and XRD were used to examine the variation of structure of surface composites after casting and solidifying. It was confirmed that the VC particles reinforced surface composites can be in situ produced on the casting surface by the cast-sintering technology. The mechanism of quickly finishing V carbonized reacts and sinter compacting in block during casting was analyzed. The wear-resistance of VC particles reinforced surface composites was examined on a MM-200 wear-test machine.

Abstract: When the pressure of CO₂ is 2 MPa, through the autoclave corrosion tests of annealed N80 steel specimens in simulated oil field water solution at different temperature, the mechanism of corrosion and the change rule of corrosion resistance with the change of temperature were discussed. In the autoclave tests, some iron elements of the specimens become Fe²⁺ ions and the Fe²⁺ ions go into the solution, which results in the corrosion weight loss. Scaling develops because the CO₃^2- ions in the simulated oil field water solution react with iron elements of the specimen. To QPQ treated specimens, with the increase of temperature, the compactness of the scaling increase, the corrosion weight loss and the weight of scaling decrease. In the same temperature, the corrosion weight loss and the weight of scaling of QPQ treated specimens are both lower than that of untreated specimens.

Abstract: By constant stress tensile test, the corrosion mechanism of high temperature QPQ treated 25CrMnMo steel specimen in H₂S environment was analyzed and discussed. The γ′-Fe₄N in the ε compound layer turns into corrosion substance in the test and expands. At the surface of the ε compound layer, the corrosion layer is visible. The compound layer breaks off in little blocks for volume expansion of the corrosion substance and the exterior tensile stress. The coefficient of diffusion of hydrogen atom in the ε compound layer is very low, that decrease the probability of the hydrogen-induced corrosion of high temperature QPQ treated specimens in H₂S environment.