45钢渗Zr合金层摩擦磨损性能及电化学性能研究

发布时间：2018-01-25 23:09

本文关键词： 45钢双辉等离子渗金属 Zr合金层摩擦磨损电化学腐蚀　出处：《太原理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：45钢作为一种优质的碳素结构钢，具有较为优良的切削加工性能和良好的机械性能，被广泛应用在机械制造业及汽车等领域。但45钢相对较差的耐磨损能力和耐腐蚀性能，大大地限制了其在特殊环境中的应用。本课题采用双辉等离子渗金属技术对45钢进行了等离子渗Zr处理。分别研究了800℃-950℃渗金属温度对Zr合金化层组织、成分、结构和硬度的影响，并且对合金化层形成机制进行了研究。通过对比分析45钢基材及其不同温度渗Zr试样在不同载荷下的摩擦磨损性能以及在0.5mol/L的H2SO4溶液中的电化学腐蚀性能，分别探讨了Zr合金层摩擦学性能和耐腐蚀性能的改善机理。得出如下主要结论： (1)利用双辉等离子渗金属技术在45钢表面渗Zr，可以在其表面形成连续均匀致密并且与基体以扩散连接的渗Zr合金层。经过800℃-950℃不同温度渗Zr处理后，，在45钢基材表面形成的Zr合金层厚度在5μm-21μm之间。并且随着渗金属温度的增加，形成的Zr合金层的厚度也随之增加。不同温度下形成的Zr合金层均由Zr2Fe、ZrC、ZrC0.7、Fe3C组成。 (2)45钢经过不同温度渗Zr处理后的表面硬度较未处理的基材均有显著的提高。45钢基材的硬度约为217HV0.025，而800℃-950℃渗Zr后的表面硬度值为673HV0.025~893HV0.025。渗Zr处理后硬度的增加主要是与Zr的固溶强化作用以及硬质ZrCx的形成有关。 (3)不同温度渗Zr试样在载荷为1N和2N时的摩擦系数分别在0.08-0.4以及0.1-0.4之间波动，均小于相同实验条件下45钢基材的平均摩擦系数(0.55和0.5)。850℃、900℃以及950℃渗Zr试样在1N载荷下比磨损率分别是45钢基材的12.1％、3.2％以及2.3％，在2N载荷下的比磨损率分别是45钢基材的6.7％、3.8％以及2.9％，起到了良好的耐磨以及减摩效果。载荷为5N时，850℃和900℃渗Zr层被磨穿，摩擦系数较大，但比磨损率分别是45钢基材的20.7％和77.6％，仍有一定的耐磨作用。950℃渗Zr试样的摩擦系数(0.25)明显小于45钢基材(0.5)，体积磨损量是45钢基材的9.1％，减摩和耐磨性得到一定的改善。Zr的固溶强化作用以及Zr的碳化物析出是45钢渗Zr后摩擦学性能提高的重要原因。此外，摩擦过程中渗Zr试样表面形成的ZrO2薄膜同样对试样起到了一定的保护作用。 (4)45钢经不同温度渗Zr后的试样在H2SO4腐蚀液中的耐腐蚀性能较未处理的45钢基材得到了明显的提高，其中950℃渗Zr试样的耐腐蚀性能最佳。不同温度渗Zr试样自腐蚀电位较45钢基材明显正移。与45钢基材相比，渗Zr试样的腐蚀电流密度明显下降。从钝化电流密度来看，850℃渗Zr试样钝化电流密度大于基材，900℃和950℃渗Zr试样的钝化电流密度小于基材。且不同温度渗Zr试样均发生了二次钝化，二次钝化所对应的电流密度明显小于同电压对应下的45钢基材。不同温度渗Zr试样交流阻抗谱的电阻值均大于未处理的45钢基材。Zr是一种活泼金属，渗Zr试样暴露在空气中表面易形成一层ZrO2氧化膜，这层惰性膜使得渗Zr合金层显示出优良的耐腐蚀性能。
[Abstract]:45 steel is a kind of high-quality carbon steel, cutting with excellent performance and good mechanical properties, is widely used in machinery manufacturing and automotive fields. But the wear resistance of 45 steel and relatively poor corrosion resistance, greatly limits its application in special environment.
This paper using double glow plasma surface alloying technique of plasma surface treatment on Zr steel were studied. The 45 components of 800 DEG -950 DEG alloying temperature on Zr alloy layer microstructure, hardness, impact and structure, and the formation mechanism of alloying layer were studied. Analysis of friction and wear properties of 45 steel substrate and different the temperature of infiltration Zr specimen under different loads as well as in the H2SO4 0.5mol/L solution in the electrochemical corrosion properties were discussed by comparing the Zr alloy tribological properties and corrosion resistance improvement mechanism. Results of this study were as follows:
(1) using the double glow plasma surface alloying technique Zr infiltration on the surface of 45 steel, can form a continuous uniform on the surface of Zr alloy and the infiltration layer is connected with the substrate by diffusion. After 800 -950 degree centigrade temperature of different permeability after Zr treatment, the thickness of Zr alloy layer formed on the surface of 45 steel substrate in 5 M-21 m. And with the increase of alloying temperature, Zr alloy layer thickness increases. Zr alloy layer formed at different temperatures were determined by Zr2Fe, ZrC, ZrC0.7, Fe3C.
(2) substrate has 45 surface hardness of steel after different temperature infiltration after Zr treatment compared with untreated.45 steel significantly improved the surface hardness of about 217HV0.025, while the 800 DEG -950 DEG Zr after infiltration of surface hardness values increase as 673HV0.025~893HV0.025. permeability after Zr treatment and Zr hardness is mainly solid solution strengthening effect and the formation of hard ZrCx.
(3) Zr samples at different temperature seepage load for the friction coefficient of 1N and 2N respectively in 0.08-0.4 and 0.1-0.4 between the fluctuations were less than the average friction coefficient of 45 steel substrate under the same experimental conditions (0.55 and 0.5).850 C, 900 C and 950 C infiltration Zr specimen in 1N load wear rate respectively 45 steel substrates 12.1%, 3.2% and 2.3%, the specific wear rate under 2N load were 6.7% 45 steel substrates, 3.8% and 2.9%, played a good wear resistance and antifriction effect.
When the load was 5N, 850 degrees and 900 degrees Zr infiltration layer is worn, the friction coefficient is larger, but the wear rate is respectively 45 and 77.6% of the 20.7% steel substrate, still have the friction coefficient of.950 C wear certain osmotic Zr samples (0.25) were less than 45 steel substrate (0.5), wear volume is the 45 steel substrate 9.1%, antifriction and wear resistance can be improved.Zr solid solution strengthening effect and carbide precipitation in Zr is an important reason to improve the tribological properties of Zr steel after 45 infiltration. In addition, the ZrO2 thin film in the friction process infiltration Zr samples formed on the surface of the sample also plays a certain protective effect.
(4) 45 steel by 45 steel substrate at different temperatures in the H2SO4 sample Zr after infiltration of corrosive liquid corrosion resistance than untreated has been significantly improved, of which 950 DEG C osmotic Zr corrosion resistance of the sample is the best. Different temperature infiltration Zr samples the corrosion potential of the 45 steel substrate was shifted positively. With 45 steel substrate, the corrosion current density of Zr specimen permeability decreased significantly. The passive current density, 850 C infiltration Zr specimen passive current density is greater than the substrate, 900 degrees and 950 degrees infiltration samples of Zr passivation current density is less than the substrate. And different temperature Zr infiltration samples occurred two times passivation, the corresponding current density the two passivation is significantly less than the 45 steel substrate with voltage under different temperature. The corresponding permeability resistance of Zr sample AC impedance values were more than 45 steel substrate.Zr untreated is a reactive metal infiltration, Zr samples exposed in the air surface to form a layer of oxide film ZrO2, This inert film makes the Zr alloy layer show excellent corrosion resistance.

【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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