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Surface Modification Of The Additive And Mechanism Of Nano-spheroidizing Process, Anti-wear And Friction Reduction During Friction And Wear

Posted on:2012-07-26Degree:MasterType:Thesis
Country:ChinaCandidate:J T WangFull Text:PDF
GTID:2131330335959575Subject:Materials Science and Engineering
Abstract/Summary:PDF Full Text Request
The self-repairing technology is a new technology which can form a uniform and dense self-repairing layer on the metal surface of the friction pairs during friction and wear. Friction and wear of the metal-to-metal surface in the initial friction stage will turn into that of self-repairing protective layers. Thus it can reduce wear loss of the friction pair, and improve the properties of the wear resistance and friction reduction.The dispersion process of the self-repairing powder in the lubricating oil using different dispersants was studied, and the tribological properties of the self-repairing powders were researched by AMSLER friction and wear tester to explore the anti-wear and friction-reducing mechanism in this paper. The conclusions can be drawn from the experiments as follows:1,The dispersive property was studied by the different modifiers and modification processes. Polymerization grafting process by oleic acid modifier can improve the suspending time in lubricating oil. The dispersion of powder heat-treated at 1000℃is poor than that of the initial powder.2,A protective surface tribo-layer can generate on the worn metal surface during friction and wear. Friction coefficient reduces gradually in the initial stage of the test. When the self-repairing layer covers the metal surface, friction coefficient keeps stable to a minimum value.3,In the contrast of different amount and mixture ratio of the additives, it is found that powder with mixture ratio 8:2 and adding amount 1.5% possesses a better tribological performance. The powder modified by sodium dodecylbenzenesulfonate shows more excellent tribological properties. It can minimize friction coefficient remarkably in less than 3h to 0.01 and keep stable to the end of the test.4,The particles in the used oil were examined by SEM after test. It shows that spherical particles can be formed in the lubricating oil which possesses a low friction coefficient. The higher a ball rate, the lower friction coefficient is. The roughness test suggested that friction coefficient maybe has no obvious relationship with the worn surface roughness.5,The protective layer and the formation mechanism of the spherical particles maybe explained as follows:(1) The hydroxyl magnesium silicate belongs to layer silicate. Under the cyclic contacting stress and tribo-chemical interaction, sliding between the layers can take place. The additive powders can be deformed and stretched. Some powders can absorb on the metal surface and deposit on the worn area; A protective layer can generate on the worn metal surface. (2) Under the shearing stress and interactions among the additive particles, wear debris and friction pairs, the irregular additives gradually forms spherical particles and bear the contacting stress as micro-ball bearing between the friction pairs resulting in sharp reduction of friction coefficient.
Keywords/Search Tags:Self-repairing, Surface modification, Friction and wear, Nano-spheroidizing, Anti-wear and friction reduction
PDF Full Text Request
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