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 共查询到10条相似文献,搜索用时 93 毫秒
1.
Y. Chen  H. M. Wang   《Applied Surface Science》2003,220(1-4):186-192
TiC reinforced composite coating on γ-TiAl alloy was successfully fabricated by laser surface alloying with carbon. The fine TiC reinforcing phase had a gradient distribution in the coating, and its growth morphology of TiC in laser surface alloyed coating was in unique faceted platelet-like. The composite coating exhibited high hardness and excellent high-temperature sliding wear resistance.  相似文献   

2.
Because of its biocompatibility, superelasticity and shape memory characteristics, NiTi alloys have been gaining immense interest in the medical field. However, there is still concern on the corrosion resistance of this alloy if it is going to be implanted in the human body for a long time. Titanium is not toxic but nickel is carcinogenic and is implicated in various reactions including allergic response and degeneration of muscle tissue. Debris from wear and the subsequent release of Ni+ ions due to corrosion in the body system are fatal issues for long-term application of this alloy in the human body.This paper reports the corrosion and wear properties of laser surface modified NiTi using Mo and ZrO2 as surface alloying elements, respectively. The modified layers which are free from microcracks and porosity, act as both physical barrier to nickel release and enhance the bulk properties, such as hardness, wear resistance, and corrosion resistance. The electrochemical performance of the surface modified alloy was studied in Hanks’ solution. Electrochemical impedance spectroscopy was measured.  相似文献   

3.
The present work describes the surface improvement and biocompatibility of TiAl24Nb10 intermetallic alloy using rf plasma nitriding. The nitriding process was carried out at different plasma power from 400 W to 650 W where the other plasma conditions were fixed. Grazing incidence X-ray diffractometry (GIXRD), Auger electron spectroscopy (AES), tribometer and a nanohardness tester were employed to characterize the nitrided layer. Further potentiodynamic polarization method was used to describe the corrosion behavior of the un-nitrided and nitrided alloy. It has been found that the Vickers hardness (HV) and corrosion resistance values of the nitrided layers increase with increasing plasma power while the wear rates of the nitrided layers reduce by two orders of magnitude as compared to those of the un-nitrided layer. This improvement in surface properties of the intermetallic alloy is due to formation of a thin modified layer which is composed of titanium nitride in the alloy surface. Moreover, all modified layers were tested for their sustainability as a biocompatible material. Concerning the application area of biocompatibility, the present treated alloy show good surface properties especially for the nitrided alloy at low plasma power of 400 W.  相似文献   

4.
郑必举  胡文 《强激光与粒子束》2014,26(5):059003-300
通过脉冲激光器(Nd-YAG)在AZ91D镁合金基底上熔覆Al+SiC粉体。采用扫描电子显微镜、能量色散谱(EDS)和X-射线衍射测定分析熔覆层的显微组织、化学成分和物相组成。研究表明:Al+SiC涂层主要由SiC,β-Mg_(17)Al_(12)及Mg和Al相组成,激光熔覆层与镁合金基底表现出良好的冶金结合。所有样品都具有树枝状结构,且随着SiC质量分数的增大,树枝状和胞状结构的间隔变得更大。熔覆涂层的表面硬度高于基底,并且随着熔覆层中的SiC质量分数的增加而增大,SiC质量分数为40%的熔覆层具有最大的显微硬度,达到180 HV,然而质量分数为10%的熔覆层硬度为136 HV。销盘滑动磨损试验表明,复合涂层中的SiC颗粒和原位合成的Mg_(17)Al_(12)相显著提高了AZ91D镁合金的耐磨损性,其中,SiC质量分数从10%增加到30%过程中磨损体积损失逐渐减少,SiC质量分数在20%~30%时熔覆层具有最好的耐磨性。  相似文献   

5.
Titanium alloys are very attractive materials because they have high specific strength, excellent corrosion and erosion resistance in many active environments. However, their low hardness values and poor tribological properties require improvement of their surface properties. The present study is concerned with the fabrication of Zr and Zr-N alloying layers in the surfaces of Ti-6Al-4V substrates by plasma surface alloying technique. The microstructure, chemical composition and hardness of the surface alloying layers were analyzed to understand the mechanisms of surface alloying and hardness improvement. The Zr and Zr-N surface alloying layers formed were homogeneous and compact, in which the surface alloying elements all displayed gradient distributions. The Zr and Zr-N surface alloying layers all enhanced the surface hardness of Ti-6Al-4V alloy. Zr-N surface alloying resulted in greater improvement in hardness and the maximum microhardness of (1.37 ± 0.04) × 103 HK was obtained at the subsurface, which was much higher than that of the untreated Ti-6Al-4V alloy. The Zr-N surface alloying layer consisted of an outer nitride layer and an inner diffusion zone of Zr and N, and its very high hardness owed to the formation of the nitride layer. The mechanism of hardness improvement of Zr surface alloyed Ti-6Al-4V alloy was solid solution strengthening.  相似文献   

6.
铁基合金激光熔覆层高温润滑磨损性能   总被引:3,自引:3,他引:0       下载免费PDF全文
 为提高40Cr合金钢的表面耐磨性,采用预置激光熔覆法在40Cr基体表面制备铁基合金涂层, 利用扫描电镜观察分析熔覆层显微组织形貌,用显微硬度仪测试熔覆层截面显微硬度,用摩擦磨损试验机测定在润滑条件下基体、熔覆层的摩擦系数随温度变化的规律。研究结果表明:熔覆层与基体实现良好冶金结合,熔覆层横截面微观组织呈现平面晶、树枝晶和胞状晶分布;熔覆层硬度值介于617.5~926.6 HV0.2之间,基体硬度介于205.2~278.2 HV0.2之间;在200 ℃以下,熔覆层摩擦系数在磨程中趋于平稳,在0.1附近轻微波动,小于基体平均摩擦系数;当温度超过200 ℃,油膜分解,引发润滑失效,磨损方式向干摩擦转化,磨损机理从微切削磨损主导向粘着磨损、磨粒磨损和氧化磨损复合磨损方式转化。  相似文献   

7.
通过采用CO_2激光对TC_4合金进行TiN表面合金化处理,探讨了激光功率对合金化层组织和硬度的影响。结果表明,激光合金化试样存在组织不同的三个区域,分别为TiN合金化层,基底熔凝层和淬火层。TiN合金化层由钛合金基体和TiN组成,其中TiN呈现颗粒和树枝晶两种形态。基底熔凝层为定向生长的柱状晶,基底淬火层为针状马氏体。TiN激光合金化层的硬度在700~1100HV之间,约为TC_4合金的2~4倍。  相似文献   

8.
In the present work, a novel process has been developed to improve the tribological and corrosion properties of austenitic stainless steels. Efforts have been made to deposit titanium coatings onto AISI 316L stainless steel by magnetron sputtering, and then to partially convert the titanium coatings to titanium oxide by thermal oxidation. The resultant coating has a layered structure, comprising of rutile-TiO2 layer at the top, an oxygen and nitrogen dissolved α-Ti layer in the middle and a diffuse-type interface. Such a hybrid coating system showed good adhesion with the substrate, improved corrosion resistance, and significantly enhanced surface hardness and tribological properties of the stainless steel in terms of much reduced friction coefficient and increased wear resistance.  相似文献   

9.
The weight reduction of mechanical components is becoming increasingly important, especially in the transportation industry, as fuel efficiency continues to improve. Titanium and titanium alloys are recognized for their outstanding potential as lightweight materials with high specific strength. Yet they also have poor tribological properties that preclude their use for sliding parts. Improved tribological properties of titanium would expand the application of titanium into different fields.Laser alloying is an effective process for improving surface properties such as wear resistance. The process has numerous advantages over conventional surface modification techniques. Many researchers have reported the usefulness of laser alloying as a technique to improve the wear resistance of titanium. The process has an important flaw, however, as defects such as cracks or voids tend to appear in the laser-alloyed zone.Our group performed a novel laser-alloying process using a light-transmitting resin as a source for the carbon element. We laser alloyed a surface layer of pure titanium pre-coated with polymethyl methacrylate (PMMA) and investigated the microstructure and wear properties. A laser-alloyed zone was formed by a reaction between the molten titanium and thermal decomposition products of PMMA at the interface between the substrate and PMMA. The cracks could be eliminated from the laser-alloyed zone by optimizing the laser alloying conditions. The surface of the laser-alloyed zone was covered with a titanium carbide layer and exhibited a superior sliding property and wear resistance against WC-Co.  相似文献   

10.
Composite coatings mainly containing titanium carbides and borides were produced by laser surface alloying of Ti-6Al-4V with graphite and boron mixed powders. The test results show that the coatings have higher hardness (1600-1700 HV0.1) and are more resistant to wear than the as-received sample. Laser scanning speed and the content of alloying elements (weight ratio of graphite to boron) have an effect on both the microstructure and the wear resistance of the coatings. TEM results show that strip titanium carbides and borides grow alternately and thus restrain the formation of coarse needle-like TiB and dendritic TiC crystals produced by laser alloying of titanium alloys with boron and graphite separately.  相似文献   

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