| Summary: | 碩士 === 南臺科技大學 === 機械工程系 === 107 === The purpose of this research is to utilize liquid polysilazane macromolecule precursor for surface protection and strengthening. Liquid polysilazane macromolecule precursor can be converted into ceramic materials through high temperature treatment in inert or oxidative environment, also known as Polymer Derived Ceramic (PDC). The mechanical properties of this ceramic material in high temperature are quite stable, strong abrasive resistance, good heat dissipation and high hardness. Due to its liquid property it is easy to process for manufacturing and to utilize for the tests of anti-wear, hardness, hydrolysis resistance and other mechanical tests.
Liquid polysilazane macromolecule precursor is brush-coated on the surface of the anodic aluminum alloy and controlled the formation of Silicon Oxynitride carbide, SiCNO film through different pyrolytic temperatures of 400, 500 and 600°C for achieving surface strengthening effect. The result shows in the TEM (Transmission Electron Microscope) image that SiC film can be detected on the surface of the anodic aluminum alloy substrate compactly and its thickness is about 40 nm. Silicon Oxynitride carbide ceramic penetrates the nano anodic nano-pores about 11 μm. After wear test in 2160 meters, the weight loss rate(weight loss/original weight) of SiCNO coated aluminum alloy pyrolyzed at 600°C is about 0.004% that is much lower than that of pure 7003 aluminum alloy, 0.5% and anodic aluminum alloy 0.023%. And the surface hardness of SiCNO coated aluminum alloy can achieve 6-7 GPa that is twice higher than that of anodic aluminum alloy, 3-4 GPa.
The other experiment is to measure the hydrolysis of aluminum nitride surface coated by the amorphous SiCNO ceramic film. In the X-ray diffraction pattern, the crystallinities of the pure aluminum nitride and SiCNO coated aluminum nitride are completely the same. During the hydrolysis test for two weeks, the pH value of the SiCNO coated aluminum nitride still maintains stable. This result shows the direct evidence that SiCNO ceramic film has strong anti-hydrolysis ability.
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