螺杆的激光表面合金化强化研究

提出了采用激光表面合金化的方法对注塑机和挤出机螺杆表面进行强化,以提高 其抗高温粘着磨损性能,延长注塑机使用寿命。对激光合金化工艺参数进行了优化设 计。结果表明,螺杆表面进行激光纳米合金化复合处理后,合金化层与基体形成了牢固的 冶金结合,表面平均硬度由原来的HV420提高到HV620,螺杆表面的的耐磨性提高了 2．2倍;初步估计使用寿命至少提高2倍。     

纳米晶Ni-Co合金镀层在汽车减震器活塞杆上应用的可行性

在汽车减震器活塞杆用调质态45~#钢表面分别制备纳米晶Ni-Co合金镀层和镀铬层。通过比较纳米晶Ni-Co合金镀层、镀铬层及45~#钢基体的耐蚀性和耐磨性,探讨纳米晶Ni-Co合金镀层在汽车减震器活塞杆上应用的可行性。结果表明:纳米晶Ni-Co合金镀层的耐蚀性优于镀铬层和45~#钢基体的耐蚀性;耐磨性也良好,优于45~#钢基体的耐磨性。将纳米晶Ni-Co合金镀层应用在汽车减震器活塞杆上,能够起到良好的腐蚀保护和抗磨损作用。     

电刷镀镍对30Cr13钢耐腐蚀和力学性能的影响

在30Cr13钢表面电刷镀镍以实现对钢构件的快速修复。采用扫描电子显微镜(SEM)和能谱仪(EDS)考察了电刷镀镍层的表面形貌和元素分布。通过动电位极化曲线测试、洛氏硬度测量及摩擦磨损试验对比了30Cr13钢电刷镀镍层前后的耐腐蚀性能和力学性能。结果表明，电刷镀镍层表面呈胞状结构，厚度可达20μm，与基体结合良好。与30Cr13钢基体相比，电刷镀镍层的腐蚀电位更正，腐蚀电流密度降低了1个数量级，即耐腐蚀性能更好。30Cr13钢和电刷镀镍层的洛氏硬度分别为34.09 HRC和45.72 HRC，电刷镀镍层的耐磨性比30Cr13钢好。     

20钢复合表面处理工艺与性能的研究

20钢经渗碳加淬火与回火，获得回火马氏体组织。其渗碳层的硬度及耐磨性虽能满足零件的使用要求，但变形较大，存在重复加热等缺点。该钢经渗碳处理后，再进行高频感应加热表面淬火，不仅能使表面达到高硬度、高耐磨性，而且简化了工艺流程，提高了生产效率，减少了热处理变形。     

Q235钢表面电火花沉积铁基非晶改性层及其性能

采用电火花沉积技术在Q235钢表面制备了Fe基改性层，以提高Q235钢的硬度、耐磨性和抗高温氧化性。通过X射线衍射(XRD)、扫描电镜(SEM)、能谱仪(EDS)和高温循环氧化试验对比了基体和改性层的微观结构及抗高温氧化性能。结果表明，所得改性层为非晶态结构，在700°C退火6 h能实现晶化转变；改性层厚度约为12.5μm，表面呈现丘陵状形貌，与基体之间存在很好的冶金结合；电极成分中的Al、Cu和Sn分布于改性层整个表面，并且在凸起和凹陷处的含量更高；相对于基体，改性层具有更好的抗高温氧化性能。改性层的显微硬度为265.90 HV，高于基体和晶化转变改性层，耐磨性也更优。     

表面等离子熔覆强化16Mn钢的研究

在常压下采用等离子表面熔覆技术,对涂覆合金粉末的16Mn钢表面进行表面合金化处理达到表面强化目的。扫描电镜(SEM)显示合金表面组织明显细化,更多活性原子的产生大大加快了其合金化过程,使金属硬度显著提高。     

一种卵石层钻进用金刚石钻头的研制与试验

文章通过分析金刚石钻头钻进卵石层的特点及钻头破坏形式,采用三明活钻齿提高胎体内外层耐磨性,加入辅助磨料、采用球磨工艺提高胎体本身的耐磨性,钻头钢体表面硬化提高钢体寿命等相关技术,使金刚石钻头能正常消耗完工作层,从而使金刚石钻头的寿命和时效有较大幅度的提高,试验钻头与工地上正在使用的烧结金刚石钻头相比较,最高寿命提高1.5倍,最低寿命提高1.14倍,钻进时效平均提高33％,钻进寿命平均提高1.5倍.     

轧辊凸包状毛化铬镀层的耐腐蚀性能研究

为了提高毛化特征轧辊的耐磨性,在制造9Cr2Mo钢轧辊表面电沉积40μm凸包状毛化铬镀层。通过电化学测试和盐雾试验研究了镀铬层和9Cr2Mo钢基体的腐蚀行为。电化学测试表明,镀铬层的耐蚀性明显优于基体。扫描电镜观测表明,经盐雾试验51 h的基体出现大量腐蚀产物FeO,而镀铬层腐蚀产物细小且集中在表面裂纹附近,主要成分同样为FeO。镀铬层截面金相观察表明,盐雾通过铬层裂纹进入镀层和基体界面产生腐蚀,腐蚀产物通过裂纹通道扩散出来。     

电压对电刷镀三价铬镀层性能的影响

在45钢表面电刷镀得到三价铬镀层,镀液组成和工艺条件为:Cr2(SO4)36H2O 0.4 mol/L,甲酸铵0.5 mol/L,氨基乙酸0.5 mol/L,H3BO30.6 mol/L,NaH2PO2 H2O 0.3 mol/L,pH=1.5,温度50°C,镀笔移动速率15 cm/s。研究了电压对镀铬层显微结构、表面粗糙度、厚度、显微硬度和耐磨性的影响。随电压增大,镀层厚度增大,显微硬度和耐磨性均先提高后降低。电压为14 V时,镀层的表面平整,粗糙度为2.387μm,显微硬度为602 HV,耐磨性最好。     

低碳球铁激光表面合金化组织和性能分析

本文对低碳球铁进行了激光表面合金化处理的实验研究表明,在低碳球铁基体上涂覆铬铁合金粉末进行激光表面合金化处理后组织非常细小,合金化层与母体之间的结合质量良好。低碳球铁激光表面处理后,母体表面的硬度都大大提高,母体的表面硬度由HV300左右最高提高到HV1200左右,低碳球铁表面激光强化的效果显著。     

合金钢导套微损伤外表面的修复研究

利用电镀技术并辅助适度的低温热处理,镀覆Ni-Si C纳米复合镀层作为修复层,修复合金钢导套微损伤外表面。采用扫描电镜表征修复后导套外表面的显微结构,用划痕法检测修复层的附着强度,并通过干摩擦试验和盐雾试验检测修复后导套外表面的耐磨性能和耐蚀性能。结果表明,修复后导套外表面平滑、均匀,组织结构致密,修复层附着牢固;修复后导套外表面的磨损量和腐蚀率均低于全新导套,磨痕形貌和腐蚀形貌也不同。Ni-Si C纳米复合镀层能够起到减摩和防护的双重作用,修复后导套外表面的耐磨性能和耐蚀性能均符合预期。     

Study on the tribological performance of ceramic coatings on titanium alloy surfaces obtained through microarc oxidation

Through microarc oxidation, a ceramic coating is directly formed on the surface of Ti6Al4V alloy, by which its surface property is greatly improved. Microstructure, phase composition and tribological performance of the coatings were characterized. The results showed that the coating with 10-μm thickness is compact in the inner layer and porous in the surface layer. The coating is mainly composed of rutile and anatase TiO₂. The tribological behavior of the microarc oxidation ceramic coating under dry sliding against SAE52100 steel was evaluated on a ball-on-disc test rig. The Ti6Al4V alloy was characterized by adhesion wear and scuffing under dry sliding against the steel, while the polished ceramic coating experienced much abated adhesion wear and scuffing under the same testing condition. The polished ceramic coating showed good friction-reducing and fair antiwear ability in dry sliding against the steel. This is attributed to the smooth surface and rutile TiO₂.     

新型金属-陶瓷覆层材料的研究

采用真空液相烧结技术。在钢基体表面制备三元硼化物硬质合金覆层。将三元硼化物硬质合金的优异性能赋予钢基体表面。获得耐磨抗蚀、界面结合强度高的新型硬质合金覆层材料。对三元硼化物硬质合金和钢基体的界面微观结构和界面区元素分布利用SEM-EDS进行分析。发现硬质合金覆层和钢基体之间形成了一个具有一定厚度的过渡层。合金元素浓度没有发生突变。两相之间形成了良好的冶金结合。并对覆层材料的显微硬度、抗弯强度与耐腐蚀性能做了研究。结果表明，硬质合金覆层材料具有较高的显微硬度、界面结合强度和优异的耐腐蚀性能。     

热浸渗铝硅合金Q235钢的抗高温腐蚀性能研究

研究了Q2 35钢经热浸渗纯铝和不同硅含量的铝合金后的抗高温氧化和抗热腐蚀性能 ,比较了纯铝渗层和铝硅合金渗层的抗高温腐蚀性能 ,并分析了硅元素的作用。结果表明 ,Q2 35钢经热浸渗纯铝和铝硅合金后的抗氧化性能基本接近不锈钢 ,而抗热腐蚀性能则明显优于不锈钢     

Investigation of tribological properties of micro-arc oxidation ceramic coating on Mg alloy under dry sliding condition

To enhance wear resistance of Mg alloy, micro-arc oxidation (MAO) ceramic coatings on Mg substrate were prepared in silicate electrolyte under various currents. It was found that the surface roughness and thickness of MAO coating were increased with the increase of current. The dry tribological tests showed that the friction coefficient and wear resistance of thicker coatings (obtained under currents of 3?A and 4?A) were much higher than that of Mg alloy and the thin coating (obtained under current of 2?A), meanwhile the lifetime of the coating obtained under 4?A was longer than the other coatings under higher load. The wear type of thin MAO coating was slight abrasive wear under low load, whereas translated to severe adhesive wear under high load. While the main wear mechanism of thick MAO coating was slight abrasive wear or scratch under the given test condition, which was attributed to the thick intermediate layer improved load support for the soft substrate. The tribological study indicated that the MAO coating obtained under 4?A current had better wear resistance and life time due to its compact microstructure and thickness.     

渗铝Q235钢的渗层组织和抗高温氧化性能

分析了Q2 3 5钢热浸渗铝和铝硅合金层的显微组织 ,并对其抗高温氧化性能进行了研究。热浸渗层由镀层 (表层 )和化合物层 (内层 )两层组成 ,金相和X射线能谱分析 (EDS)结果表明纯铝渗层的化合物层呈厚齿状 ,由η相 (Fe2 Al5)组成 ;铝硅合金渗层的化合物层呈薄带状 ,由Si合金化的η相即Fe2 (Al Si) 5组成。热浸渗层经扩散退火后 ,表面镀层消失 ,渗层由表及里依次出现 η相、ζ相、β2 相、β1相和固溶体α相等过渡组织。 80 0℃高温氧化试验结果表明 ,渗纯铝Q2 3 5钢的抗高温氧化性能优于 1Cr1 8Ni9Ti不锈钢 ,硅的加入可以改善热浸工艺性能 ,但降低了渗层的抗高温氧化性能。     

铁-镍-钨合金电镀在缸套上的应用

以45钢缸套内孔表面为基体,电沉积得到Fe-Ni-W合金镀层.采用目视评价、显微硬度计.中性盐雾试验,盐水浸泡试验及干性条件的摩擦磨损试验等方法,研究了Fe-Ni-W合金镀层的外观、显微硬度、耐蚀性、耐磨性等性能.结果表明,Fe-Ni W合金镀层光亮、细致,镀层在最佳温度500～650℃下热处理2h后硬度最高可达130...     

Nanocrystallization of aluminized surface of carbon steel for enhanced resistances to corrosion and corrosive wear

Aluminizing is often used to improve steel's resistances to corrosion, oxidation and wear. This article reports our recent attempts to further improve aluminized carbon steel through surface nanocrystallization for higher resistances to corrosion and corrosive wear. The surface nanocrystallization was achieved using a process combining sandblasting and recovery heat treatment. The entire surface modification process includes dipping carbon steel specimens into a molten Al pool to form an Al coat, subsequent diffusion treatment at elevated temperature to form an aluminized layer, sandblasting to generate dislocation network or cells, and recovery treatment to turn the dislocation cells into nano-sized grains. The grain size of the nanocrystallized aluminized surface layer was in the range of 20–100 nm. Electrochemical properties, electron work function (EWF), and corrosive wear of the nanocrystalline alloyed surfaces were investigated. It was demonstrated that the nanocrystalline aluminized surface of carbon steel exhibited improved resistances to corrosion, wear and corrosive wear. The passive film developed on the nanocrystallized aluminized surface was also evaluated in terms of its mechanical properties and adherence to the substrate.     

Tribological behaviour of semisolid–semisolid compocast Al–Si matrix composites reinforced with TiB2 coated B4C particulates

The purpose of this paper is to provide a deeper understanding of the wear behavior of the sol–gel coated B₄C particulate reinforced A356 matrix composites. A typical microstructure of the composite consists of relatively large primary phase globules which are surrounded by B₄C particles. In fact the globules themselves are B₄C particles free and consequently the sample is not homogeneous on a scale smaller than the globule size. The wear sliding test disclosed that the wear rate of the coated B₄C reinforced composites is less than that of the unreinforced alloy and decreases with increasing volume fraction of B₄C particulates. As the hardness of the composites is higher, this reduces the cutting efficiency of the abrasives and consequently the abrasion wear loss. Once the particles fracture or loosen from the matrix alloy, they can be removed easily from the matrix, contributing to the material loss. Two kinds of debris present irregular-shaped flake, which has withstood a large of plastic deformation and then pull off from the surface. During the sliding wear, Iron is transferred to the surface of the composites from the steel counterface forming the iron-rich layer on the contact surfaces which increases with increasing the B₄C content and is substantially harder than the bulk material largely because it contains a fine mixture of Fe phase, Al and B₄C.     

Microstructure and properties of Ni-WC gradient composite coating prepared by laser cladding

In this study, an Ni-based gradient composite coating reinforced with WC was prepared on a Q345R steel substrate by laser cladding. The Ni-WC composite coating was designed as a multilayer structure with gradient composition. The coating started with a layer of C276 alloy with 10 wt% WC on the substrate, and the subsequent layers were composed of Ni60 alloy with different WC contents (10, 30, and 50 wt% WC). The overall morphology, phase composition, and microstructure of the coatings were investigated. The microhardness and the wear properties of each layer of the coatings were also evaluated. The results showed that the gradient composition design was beneficial for reducing the cracking tendency. The coating was composed of an Ni-based matrix, WC, and multiple carbides and borides hard phases. With increasing WC content in the layers, the hard phases exhibited regional distribution characteristics. The WC reinforcement particles underwent different types of dissolution during the cladding process. From the surface to the substrate, the average microhardness of the coating was 1053.5 HV_0.2, 963.4 HV_0.2, 859.0 HV_0.2, 441.7 HV_0.2, and 260.5 HV_0.2. The wear tests revealed that the coefficient of friction and the wear loss values of the four layers were all lower than those of the substrate, demonstrating enhanced wear resistance.