ABSTRACT
(Ti,Al)N coating and nano-multilayers were deposited by multi-arc ion plating on the nano-composite Ti(C,N)-based cermets with high mechanical properties.In the first part of the dissertation, the development and present research situation of Ti(C,N)-based cermets have been critically overviewed, which include the influence of manufacturing process and composition on the microstructures and properties of Ti(C,N)-based cermets. The multi-arc plating process and its characteristics have been introduced. The development of (Ti,Al)N coating and multilayers has been summarized. Based on above work, the purpose and significance of the dissertation have been pointed out.
The relationship among composition, microstructure and properties of Ti(C,N)-based cermets has been systematically investigated by scanning electron microscopy (SEM), energy dispersive X-ray analysis(EDS) and etc. The conclusions were obtained as follows: When the amount of C was 0.7wt%, the cermet had better microstructures and mechanical properties. The highest transverse rupture strength and hardness were found in the cermet with 16wt% Mo addition,which reached 1930MPa and 89.5 HRA, respectively. But the variation of hardness was not apparent. The influence of the addition amount of Ni on the solubility of metal elements in the binder phase has been studied, and there was a decrease of Ti,W and Mo, the variation of W and Mo was not obvious.
(Ti,Al)N coating was deposited on the Ti(C,N)-based cermets by multiarcion plating. The influence of the deposition parameters such as target power, bias voltage and gas pressure on composition, phase structure, hardness, cohesion and friction wear of (Ti,Al)N coating. The results revealed that the abrasion of (Ti,Al)N coating was grain-abrasion at room temperature. The friction coefficient reduced with the increase of bias voltage or gas pressure. When the substrates temperature was 400℃ , the ratio of target power of IAl/ITi=70/80, the bias voltage was -100V and the gas pressure was 1.0Pa, the properties of (Ti,Al)N coating was excellent.
Finally, the TiN/AlN and TiN/(Ti,Al)N nano-multilayers were deposited with different modulation periods by multi-arc ion plating, and the effects of modulation periods on the microstructures and mechanical properties of the nano-multilayers were also investigated. Some conclusions were drawn as follows: When the rotational speed of object stage was 12rpm, AlN was metastable cubic structure,which improved the mechanical properties of TiN/AlN nano- multilayers. The cohesion and hardness reached 41.0N and 3429HV, respectively. The less the modulation period varied, the stronger of the TiN/(Ti,Al)N phase grew along (111) crystal face by preferential orientation became. The hardness of TiN/(Ti,Al)N nano-multilayers was higher than that of (Ti,Al)N coating at the same processing condition.
Key words: Ti(C,N)-based cermets, Microstructure, Mechanical properity,Multi-arc ion plating, (Ti,Al)N coating, TiN/AlN nanomultilayers,TiN/(Ti,Al)N nanomultilayers
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