The air cooling rate of the Low Carbon Mn-Si-Cr steel bar with different diameter after austenitizing at 910oC and 960oC was simulated by Formaster-F Phase transforming instrument and Gleeble-1500 thermal /mechanical simulating machine. Microstructure of the specimen was observed by OLYMPUS PME3 optical microscope and FEI QUANTA200F scanning electron microscope. The hardness and impact toughness of the steel was tested by HBRV-187.5 hardness tester and JCSJ300-I instrumented Charpy impact tester. The experimental result showed that with the amount of CFB in CFB+M mixed microstructure increasing the combination of strength and toughness of the steel was improved. The higher the austenitizing temperature of the steel, the wider the air-cooling rate range obtaining CFB+M mixed microstructure. However, the steel produces mixed grain after austenitizing at 960 oC. For obtaining fine prior austenite grain size, Ti and Nb alloying element need to be added.

CCTO powders were prepared by using molten salt method in the NaCl-KCl system. The effects of temperature and holding time on phase compositions, particle morphology and size have been investigated by X-ray diffraction, scanning electron microscope and laser particle size analyzer. Using CaCO3, CuO and TiO2 as starting materials, CCTO compound could be synthesized at any temperature from 800oC to 1000oC in the NaCl-KCl system. The average particle size increased obviously with the increasing of temperature above 850 oC. Holding time had great effect on grain size and morphology.

In this work, TiC-Ni coating was synthesized on copper substrate by electro-thermal explosion ultra-high speed spraying method at the discharge voltage of 26kV. Microstructure, phase structure, elemental distribution and microhardness of the coating were studied by means of scanning electron microscope in back-scatter-electron and secondary electron, energy-dispersive analysis X-ray spectroscopy, X-ray diffraction and Vickers hardness tester. The TiC-Ni coating, which exhibits no pores or cracks, consists of an irregular spheroidal TiC phase embedded in a nearly continuous Cu0.81Ni0.19 binder. TiC particles are uniformly distributed and the size of the TiC particle of the coating is less than 1.0 m because of the solute trapping effect. The average hardness of the TiC-Ni coating is approximately 1200 HV0.3.

In this work, a new method, electro-thermal explosion ultra-high speed spraying (EEUSS), was utilized to synthesize the titanium carbide based and nickel bonded (TiC-xNi) coatings. The nickel content was varied at the weight percents of 5, 10, 15 and 20%. The microstructure and properties of the coatings were studied by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and microhardness tester, respectively. The TiC-xNi coatings had the metallurgical bonding with the substrate, and consisted of submicron grains. The grain abrasion tests results showed that the abrasion resistance of the coatings was affected by the contents of Ni.

A Fe-based amorphous composite coating doped by molybdenum was fabricated by the pulse laser cladding technology. The substrate was a low carbon steel plate. The nominal composition of the powder in the range from 100 to 200 meshes was (wt.%) Cr:14.95, Mo:25.7, B:1.24, C:3.45, Y:3.40, Fe:51.29, which was selected for the laser cladding process. The microstructure, phase composition, hardness and corrosion resistance of the coatings were characterized by means of SEM, EDS, XRD , DSC and potentiodynamic polarization test. The results show that the coating which was composed of amorphous and nanocrystal phases had the dense structure and metallurgical bonding with the substrate, meanwhile with low porosity and cracks. The addition of molybdenum played an important role in improving the corrosion resistance of the coatings. With the increasing content of molybdenum, the hardness had no significant change, while the corrosion resistance of the coatings significantly increased. From the results of polarization curves, the corrosion current density of the coating added 0 wt.% Mo is higher than that of the coatings added 2 wt.% Mo and 10 wt.% Mo. The molybdenum has a superior effect on the corrosion resistance in Fe-based amorphous composite coating.