Papers by Author: Jun Chen

Abstract: To enhance the product quality and production efficiency, we studied the kinetics of the microwave - vacuum drying of bleached shellac and optimized its technological process. Through the test, the drying curve, drying rate curve and drying constant of the bleached shellacs under different pressure were obtained and through the drying curve fitting, the drying model was obtained. And through the optimization test, the optimal conditions for the microwave - vacuum drying of bleached shellac were obtained, that is, pressure of 3000Pa, microwave power of 700W and drying time of 25min, then the products of color index of 0.9, water content of 0.0296 kg water / kg dry materials were obtained.

Abstract: The lance system is one of the important link of converter. Stable and secure of the system is a necessary condition for whole production system to function normally. The numerical simulation for a three-dimensional oxygen lance nozzle was carried out according to the fundamental parameters of PZH steel, the characteristics of the oxygen jet were analyzed and discussed. The oxygen lance nozzle with the optimum design has achieved good results in practice: the average formation time of early slag was reduced by 1 min and 23 seconds, the pure blowing time was reduced by 46 seconds, the oxygen consumption per ton steel decreased by 1.05 m³/t, the rate of dephosphorization was increased by 1.35%, the basicity of slag was reduced by 0.38, the phosphorus and sulfur distribution ratio between slag and liquid iron were also increased effectively.

Abstract: The recent shift in the design focus for aeroplanes from strength to damage tolerance has led to a subsequent shift in the focus of Ti alloy research. China first started to research Ti alloys with damage tolerance from the year 2000. The first product stemming from this research is a Ti alloy with high strength, high toughness and damage tolerance (TC21). TC21 exhibits high strength (UTS  1100MPa), high fracture toughness (K1c  70MPa.m1/2) and a low crack propagation rate (da/dN being similar to Ti-6-4 with  annealing). Another Ti alloy, named TC4-DT, has also been produced. It has moderate strength, along with high toughness and damage tolerance (UTS  900MPa, K1c  70MPa.m1/2, da/dN being similar to Ti-6-4 with  annealing). Both TC21 and TC4-DT are now undergoing rapid development, with the former alloy also being applied to a full scale aeronautical application. Both TC21 and TC4-DT have promising futures in the industry. They will be the main Ti alloys with damage tolerance utilised in the Chinese market.