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Preparation And Study Of Anodic Oxidation Self-lubrication Antifriction Composite Coating With Low Pollution On Surface Of TC4Titanium Alloy

Posted on:2014-11-05Degree:MasterType:Thesis
Country:ChinaCandidate:L LiFull Text:PDF
GTID:2181330467978099Subject:Environmental Science
Abstract/Summary:PDF Full Text Request
Titanium alloy has many advantages, such as small density, high strength, corrosion resistance, high temperature resistant. It has become the important structural material which widely used in aviation, aerospace, ships, chemical industry, national defense and civilian industry. The TC4(Ti-6Al-4V) titanium is the most widely used among them, whose dosage accounted for more than half of the total titanium alloy, but the low hardness and poor wear resistance restrict its application in practical production. Surface modification treatment of titanium alloy can improve the friction and wear properties, it has become a hot research in titanium alloy field.This article is focused on using the method of anodic oxidation-PTFE composite coating on the surface of TC4titanium alloy to prepare self-lubricating film which has friction and wear resistance. Meanwhile, analyzed for the main influence factors of surface morphology and film thickness of the titanium anode oxidation film, and using XRD, SEM and other methods to test the surface morphology and microstructure of anodic oxidation film and composite self-lubricating film, and using the friction and wear testing machine to test friction and wear properties.(1) Through the study of anodic oxidation of titanium alloy in sulfuric acid system, analyses the electrolyte concentration, NH4HF2concentration, oxidation voltage, oxidation temperature and oxidation time on surface morphology and thickness of oxide film, discuss the main factors which influence the wear-resisting property of oxidation film. The experimental results show that the change of electrolyte concentration, NH4HF2concentration and the oxidation voltage play a prominent role in surface film hole diameter and film thickness of the oxidation film, the increase of the size of the aperture with the increase of the concentration of electrolyte, voltage, aperture, and under the condition of the electrolyte(H2S04) concentration is0.3-1mol/L, oxidation voltage is60-130V, the diameter of film hole is about100-500nm; oxidation time has a great influence on the thickness of oxide film, the thickness of oxide film is4.4-11.9μm between lh-3h; and the reaction temperature is mainly influence the uniformity of surface membrane pore of the oxidation film. After determining the friction coefficient of TC4titanium alloy anodic oxidation film, it is find that the titanium alloy friction coefficient with anodic oxidation film declined significantly than the not anodized, its reduce level is related with thickness of film and uniformity of membrane pore, the more thicker of the oxidation film, the lower of friction coefficient, the test shows that the friction coefficient TC4titanium alloy is about0.45~0.5before the anodic oxidation, under the condition of the electrolyte(H2SO4) concentration is0.8mol/L, the temperature is-5℃, oxidation voltage is130V, the anodic oxidation time is3h to prepare anode oxidation film,the titanium alloy friction coefficient decline to0.35, thermal treatment this oxide film in800℃for2h under this condition, oxide film phase structure determination (XRD) shows that almost all of their component are rutile type TiO2, friction coefficient decline to0.29.(2) The preparation of anode oxidation-PTFE composite coating and the research foe its friction and wear properties. Experimental results show that under the condition of the electrolyte(H2SO4) concentration is0.8mol/L, the temperature is-5℃, oxidation voltage is130V, the anodic oxidation time is3h to prepare anode oxidation film and coats6.7%PTFE with30min, surface film were blocked by filling, and the friction coefficient significantly reduced to0.2; the friction coefficient continue reduce to0.13-0.14with20%PTFE; thermal treatment under the200-300℃after coating with6.7%PTFE, making the PTFE in the molten state and filling film hole better, the friction coefficient is declined to0.12, the self-lubricating antifriction composite coating significantly improve the wear-resisting property of titanium alloy.
Keywords/Search Tags:TC4Titanium Alloy, Anodic oxidation, PTFE, Friction and wear, Self-lubricating composite
PDF Full Text Request
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