Papers by Keyword: Heat Treating

Abstract: This article is devoted to the research into the influence of different heat treatment types on the concentration of dispersed refractory particles in amount of dispersion-strengthened metal materials. The heat treatments of metal materials were performed in several modes with different curing temperatures and cooling environments. Then, particles have been counted as the analytical system "Thixomet". The obtained data have been compared to calculations. Results of the done work are presented in the conclusion.

Abstract: The cerium dioxide films were prepared with cerium foils as raw materials by anodization in Na₂C₂O₄-NH₃∙H₂O-H₂O-(CH₂OH)₂ electrolyte. The anodic cerium oxide films were heat treated in 100~400°C and 0.5~2.5h, respectively. The heat treated anodic cerium oxide films were characterized with X-ray diffraction (XRD). The heat treated anodic cerium oxide film at 100°C is semi crystalline film. The heat treated anodic cerium oxide film at 200°C, 300°C, 350°C, 400°C, respectively for 2h, is the cerium dioxide film respectively, and has a structure of cubic fluorite respectively. The crystal structures of the cerium dioxide films become more complete with the increase of heat treatment temperature in 200 ~ 400 °C. The heat treated anodic cerium oxide film at 400°C for 0.5h, 1h, 1.5h, 2.5h, respectively, is the cerium dioxide film respectively, and has a structure of cubic fluorite respectively. The crystal structures of the cerium dioxide films become more complete with the increase of heat treatment times in 0.5h ~ 2.5h.

Abstract: The method to improving surface corrosion resistance of 6063 aluminum alloy was studied, and the mechanism of surface corrosion resistanc was discussed in theory. The results indicate that the adjustment of chemical composition is of advantage to corrosion resistance of the alloy, its property is better as Mg, Si mass ratio at about 1.55. The necessary homogenizing treatment of cast ingot subserves corrosion resistanc of aluminum extrusion, and the cast ingot should be cooled quickly after heat treatment. Significant effect of extrusion technology on erosive property is observed from aluminum alloy, aluminum extrusion has good corrosion resistance when outlet temperature is at about 510 degree centigrade.

Abstract: In the Ti-6Al-4V-ELI alloy, the alpha phase is gradually transformed into the beta phase until beta-transus temperature ( 980°C) is reached, and the transformation is completed. It is important to identify the transformation kinetics to accomplish the solution heat treatments in which a phase alpha percentage remains unchanged. Kinetics and other transformation characteristics are evaluated, as well as their influence on subsequent cooling transformations, by differential and dilatometric thermal analysis, electric conductivity measurements, hardness measurements and metallographic observation, after performing controlled thermal treatments. Starting from the mill annealed condition, samples were heated at temperatures between 650-1000 °C for 1 hour, then water quenched and subsequently heated for aging, air cooled. Finally, the mechanical properties of samples heat treated were obtained.

Abstract: The Cr-Cu-N nanocomposite thin films with copper contents ranging from 1.6 to 24.1 at.% were deposited on silicon wafer substrates using a bipolar asymmetry pulsed DC reactive magnetron sputtering system. A dense and compact structure was observed for the thin film containing higher than 10.2 at.% Cu, whereas columnar structures were revealed on the coatings with less than 10.2 at.% Cu. Heat treatments of the as-deposited thin films were held in a vacuum tube furnace at 400, 450 and 500oC for 30 minutes, respectively. It was observed that the copper atoms would diffuse to the surface to form oxide particles on the coating contained higher Cu content after heating higher than 450oC. The quantity and size of the oxide particles increased with increasing heating temperature and Cu content in the thin film. The hardness of coatings increased after heating except #D thin film containing 24.1 at.% Cu, which the softening effect was found after heating at 500oC. A granular and less dense cross-sectional morphology was observed on #D coating after heat treating at 500oC, which was responsible for the lower hardness of thin film.

Abstract: To model the microstuctural and mechanical responses of quenched metallic components, the evolution of the thermal field must be known precisely; the latter, in turn, depends on accurate values of the thermal boundary conditions. In this work, the heat transfer boundary conditions on both sides of a stainless steel disk, held horizontally while a water column impinged on its lower surface to cool it from 850°C to room temperature, were characterized as heat flux histories which are functions of the radial coordinate. Thermal responses, measured with embedded thermocouples and a computer-controlled data acquisition system, were used to estimate the heat flux histories by solving the corresponding inverse heat conduction problem (IHCP), considering radial symmetry. The optimization problem also included the estimation of sub-areas associated with different heat extraction rates on both the lower and upper surfaces of the disk. The fluctuating interaction between the water column and the cooling disk was captured in the estimated heat flux histories. The estimated thermal boundary conditions were validated by computing the thermal response at the thermocouple locations by solving the direct heat conduction problem (DHCP) with a computer program based on the finite-element method. A good agreement between experimentally determined and computed thermal responses was observed, thus verifying the methodology employed.