Study On Mechanical Energy Aided Aluminizing And Properties Of Aluminizing Layer

Based on the experiments the optimum components of the mechanical energy aided aluminizing agent and the main technical parameters ,such as temperature, time and filler size, etc, were studied in this degree thesis.New active agents and fillers were used to optimize the components and the parameters and also to reduce its cost. A aluminized layer with more than 100μm thickness could be formed by the mechanical energy aided aluminizing at 600℃for 3 hours on 08F steel.The experimental results of diffusion annealing on the aluminized steels showed that the diffusion reaction could carry on at 700℃, the complete diffusion of the aluminized layer on the steels could carry though at 800℃for 4hours. The layers only consist of lower aluminum phase like FeAl and Fe₃Al.The microstructure, surface morphologies and composition of the aluminized layer and the effects of the component of the agent on its defects were analyzed by metallographic microscope, electron probe, X-ray diffractor and transmitting electronic microscope.Excellent wear resistance of the aluminized steels was obtained due to the higher hardness, more than 800Hv_0.1, of their surface layers, and also excellent corrosion resistance to NaCl,H₂S,H₂SO₃,HNO₃ and oxidation resistance at elevated temperature of them were showed by the relative experiments. The matrix of the aluminized steels could keep its original mechanical properties because of lower aluminizing temperature.The experimental results showed that the higher aluminizing rate could also be obtained on 1Cr18Ni9 steel or pure titanium bu the mechanical energy aided aluminizing, but there was a different between they and carbon steels in a non-diffusion pure aluminium layer containing in the aluminized layer of the stainless steels and pure titanium. With observation of the experiments o mechanism of the mechanical energy aided aluminizing was analysized and discussed from different views, such an reactions among the components of the aluminizing agent, circulations of aluminizing atmosphere, friction cleaning of the aluminized surface by the fillers, formation of crystal defects on the surface by impacting and cold welding between aluminium powder and steel surface.