| Summary: | 碩士 === 國立虎尾科技大學 === 機械設計工程系碩士班 === 107 === This paper will investigate the effects of wear, tensile and fatigue properties, and average stress on cycle life for materials in different processes under wear, tensile and fatigue tests.The aluminum matrix composite containing titanium carbide particles is produced by in situ reaction and direct addition, The in situ reaction is formed by reacting a carbon- containing gas with titanium in a liquid melt to form TiC.
This study used three aluminum matrix samples, (1) aluminum alloy (Al-5.1Cu-6.2Ti), (2) aluminum matrix composites containing TiC particles formed by in situ reactions, and (3) aluminum matrix composite containing TiC particles by drectly adding. The tensile strength, the wear resistance, the fatigue strength and the sliding wear resistance of the three samples are compared. The tensile strength increased up to 21%, and the hardness increased by 20% for an aluminum matrix composite containing TiC particles by in situ reaction. The tensile strength increased by 15%, and the harness increased up to 18% for the direct addition of TiC particles to the aluminum matrix composites.
The TiC particles formed by the in situ reaction method are 10 times smaller than the direct addition method, and integrate with aluminum matrix strongly. Therefore, Aluminum matrix composites containing TiC particles are formed by in situ reactions has the better tensile properties, wear resistance, and fatigue strength than the other two samples. The tensile properties of the aluminum matrix composite material to which TiC particles are directly added is higher than the aluminum alloy.
By changing the average stress (σm) of the experiment, it was found that the cycle life (Nf) was greatly reduced. The same stress vibration (σa) and average stress (σm) conditions were found in the study. The lower the yield stress (σy) of the composite, the higher complete reverse stress (σar), and the closer the true fracture strength (σfb) is to the fracture strength (σ'f). The data results are plotted as a stress-weak mean stress curve and the stress-vibration (σar) is found to be primarily related to the true failure strength.It is mentioned that the TiC is fabricated of aluminum matrix composites by different methods, which will change the original hardness of the aluminum alloy, but the hardness increase will not directly affect complete reverse stress (σar). If the material has a crack problem, if the material has a crack problem, its cycle life (Nf) will be lower than that of a split-free aluminum-based composite with an average stress of zero.
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