45钢表面双层辉光等离子渗铝

利用双层辉光等离子表面冶金技术,以Al为欲渗合金元素,在45钢表面形成铁铝金属间化合物改性层,采用SEM、EDS、XRD等分析方法研究了改性层形貌、化学成分及相组成特点,并对其进行了结合力检测.结果表明,改性层由沉积层与扩散层组成,主要构成物相为FeAl、Fe3Al和α-Fe(Al),成分呈梯度分布,与基体结合良好.     

Influence of heat treatment on surface morphology,hardness, wear and corrosion resistance of industrial phosphate coatings

Abstract

New phosphate black coatings for the improvement of mechanical properties on metallic objects have been developed to extend life time of machinery. The performance of phosphate black coatings was evaluated by weight gain studies, micro hardness studies, abrasive wear resistance and corrosion resistant measurement by electrochemical methods. The surface morphology of the coatings was assessed by XRD, SEM and XPS. The absorption coefficient of the coatings was evaluated by UV-visible spectrometer. Salt spray analysis was carried out to follow up the corrosion and get an idea about the performance of black coatings in automobile parts. The mechanical properties were very much improved after heat treatment of coatings at 200°C.     

Novel W-based metallic glass with high hardness and wear resistance

An attempt has been made to develop a new metallic glass (MG) that combines high hardness with wear resistance. Refractory metallic films of W₃₃Ni₃₂B₃₅ (at.%) have been deposited on stainless steel and Si substrates by dc magnetron sputtering. The alloy films are glassy, have a high crystallization temperature of 873 °C and rank among the very hard metallic materials (∼24 GPa). Importantly, this MG also shows excellent wear resistance, approaching that of standard tribological materials like TiN and hence it represents one of the most wear-resistant known metallic materials. Based on its unique combination of high strength and low elastic modulus, other potential applications are also discussed.     

TC4合金双辉等离子渗Cr高温氧化行为

研究了双层辉光等离子渗Cr对TC4合金650、750、850℃恒温氧化性能的影响。结果表明：渗Cr后,表面梯度合金层显著提高了TC4合金的高温氧化性能,Ti-Cr互扩散层可有效阻止氧向基体扩散。氧化过程中,Ti、Cr向外扩散形成TiO2/Cr2O3氧化膜,其形态与氧化温度有关。850℃氧化100 h后,渗Cr试样表面形成致密Cr2O3膜,恒温氧化性能优于NiCrAlY热障涂层。     

Hot erosion wear and carburization in petrochemical furnaces

High temperature alloy stainless steels used in olefins manufacturing furnaces are exposed to extreme environmental degradation processes inclusive of carburization, oxidation and hot erosion wear. A study was undertaken to understand the hot erosion wear phenomenon in relation to substrate composition, atmosphere, temperature, time and the influence of carburization. An erosion wear test rig was designed and constructed to simulate the wear degradation process up to 1200°C. Results have shown a surprising relationship between erosion wear rate and temperature for the most prominent stainless steel alloy used in the industry. A novel coating technology was developed for mitigation that enables the non‐line‐of‐sight application of protective macro‐coatings typically 1 to 5 mm in thickness. Stainless steel coupons treated with these macro‐coatings have exhibited an enhanced resistance to both oxidation and carburization. These macro‐coatings also provide superior hot erosion wear resistance as compared to the uncoated stainless steel. A thorough examination of the microstructure and micro‐mechanical properties of the coatings is presented. Targeted applications include petrochemical furnace fittings (return bends), thermo‐wells and transfer‐line‐exchanger (TLE) surfaces. Commercial furnace trials of the prototype products have been initiated with some prototypes in field trials for over 18 months. Results of both laboratory accelerated testing and field evaluation will be discussed.     

冷处理对42CrMo钢硬度和耐磨性的影响

在42CrMo钢常规处理的基础上增加了冷处理,研究浅冷处理和深冷处理对42CrMo钢硬度和耐磨性的影响。结果表明,经浅冷处理和深冷处理后,42CrMo钢中残留奥氏体向马氏体发生转变,且碳化物析出增多,致使钢的硬度和耐磨性均有提升,且深冷处理后硬度和耐磨性提升幅度高于浅冷处理。     

The effects of heat treatments on hardness and wear resistance in Ni-W alloy coatings

The relationship of processing parameters, microstructure, and mechanical responses of the electrodeposited nickel-tungsten alloys exposed to elevated temperatures in the range 700-1100 °C are investigated. Reverse pulse electrodeposition technique is employed to control the tungsten content and nanocrystalline grain size of the deposits. The application of heat treatment at 700 °C on the alloy with high tungsten content (22 at.%) and small grain size (3 nm) gives hardness enhancement and a small decrease in wear resistance. Prolonging annealing duration and increasing annealing temperature promote more grain growth and reductions of both hardness and wear resistance, despite the formations of secondary phases. For alloys with lower tungsten contents (6% and 13%) and larger grain sizes (13 and 56 nm), higher degrees of grain growth coupled with monotonic decline of hardness are observed. The study indicates that the electrodeposited nickel-tungsten alloys with a high tungsten content potentially serve as strong candidates for high temperature applications.     

钛表面无氢渗碳层耐蚀性能的研究

在复杂环境下,钛合金表现不仅需要具有良好的耐磨性能,同时还须具有耐酸介质的腐蚀能力。本文采用电化学和侵蚀等分析手段,研究了钛表面无氢渗碳试样在HCl溶液和H2SO4溶液中的电化学特性及侵泡腐蚀性能。研究表明：经过无氢渗碳处理的纯钛试样在HCl和H2SO4溶液中的耐蚀性能得到大幅提高。     

Microstructure and corrosion resistance of Fe-Al intermetallic coating on 45 steel synthesized by double glow plasma surface alloying technology

A binary Fe-Al alloyed layer was synthesized on 45 steel by means of double glow plasma surface alloying technique. The corrosion-resisting layer prepared is composed of a sedimentary layer and a diffusion layer, with a total thickness of about 180 μm. The aluminum content of the alloyed layer shows gradual change from surface to the inside of substrate. The ideal profile is beneficial to the metallurgical bonding of the surface alloying layer with substrate materials. The microstructure of both layers consists of the Fe-Al intermetallic compound, which is FeAl with B2 structure in the sedimentary layer and Fe3Al with incompletely ordered DO3 structure in the diffusion layer. The protective film exhibits high micro-hardness. In comparison with the substrate of 45 steel, the corrosion resistance of the aluminized sample is much higher in 2.0% Na2S and 0.05 mol/L Na2SO4 + 0.5 mol/L NaCl mixed solutions.     

Effect of deposition parameters on adhesion, hardness and wear resistance of Sn-Ni electrolytic coatings

The present investigation has been conducted in order to determine the influence of both the chemical composition of the bath and current density employed, on the adhesion, hardness and wear resistance of electrolytic Sn-Ni coatings deposited on a steel substrate. The micro-scratch test method was employed to evaluate the coating adhesion. Three scratches were performed at progressive loads. The subsequent observation of the surface damage by means of optical microscopy allowed the determination of the critical load, defined as the smallest load at which coating delamination will occur. The composite hardness of the system was determined by means of Vickers indentation and represented as a function of the relative indentation depth (R.I.D.). The absolute hardness of the coatings was computed by using a model published previously in the literature by one of the authors. The evaluation of the wear resistance was carried out through an accelerated wear test, without lubricant, under a ball-on-disc configuration, using a ball of AISI 52100 steel as a static counterpart. The wear scar morphology was studied by Scanning Electronic Microscopy (SEM) techniques coupled with the energy dispersive X-ray analysis (EDS). The results indicate that the Sn-Ni coatings obtained by means of the chloride-fluoride bath (CF) have apparently a higher adhesion to the steel substrate and wear resistance, in comparison with the coatings which were obtained by using the pyrophosphate bath (PF), irrespective to the current density value employed during deposition. However, the hardness results indicate that the coatings obtained from the pyrophosphate bath have a better endurance against indentation loads. Such a behavior has been partially explained in terms of the different microstructural features that characterized both coatings. The CF deposits were observed to present an elongated columnar grain structure free of cracks, whereas the PF coatings were observed to have an equiaxial structure with a high crack density. The present study has allowed the conclusion that the CF coatings have an overall better performance than the PF coatings.     

固溶处理对TiB2/6061复合材料硬度及耐磨性的影响

采用氟盐法制备了TiB₂质量分数为3%的原位合成TiB₂/6061复合材料,研究了固溶温度和固溶时间对复合材料硬度和耐磨性能的影响。结果表明:TiB₂颗粒弥散分布在6061铝合金基体中,明显细化6061铝合金基体晶粒。当固溶温度一定时,随固溶时间延长,复合材料的硬度和耐磨性可获得明显提高,但固溶时间在6~10 h时,复合材料的性能变化不显著。当固溶时间一定时,随固溶温度升高,复合材料硬度和耐磨性呈现先上升后下降的趋势。3wt%TiB₂/6061复合材料经530 ℃×10 h固溶处理后,硬度和耐磨性能最佳,相较于铸态硬度值提高了79.5％,磨损量减少了59.1%。固溶处理后复合材料的磨损表面犁沟变细变浅,材料脱落现象减少。     

Improving the surface hardness and wear resistance of Ti3SiC2 by boronizing treatment

In order to modify surface properties of Ti₃SiC₂, boronizing was carried out through powder pack cementation in the 1100-1400 °C temperature range. After boronizing treatment, one mixture layer, composed of TiB₂ and β-SiC, forms on the surface of Ti₃SiC₂. The growth of the coating is processed by inward diffusion of boron and obeys a linear rule. The boronizing increases the hardness of Ti₃SiC₂ from 3.7 GPa to a maximal 9.3 GPa and also significantly improves its wear resistance.     

An investigation of molybdenum surface reinforcement on the hardness and wear properties of AISI 630

AISI 630 stainless steel (SS) surface has been reinforced with molybdenum (Mo) using gas tungsten arc (GTA) as a heat source. The optimum GTA heat source conditions have been finalised based on the proper fusion of base metal. The microhardness of the Mo-reinforced AISI 630 SS was found to be 502?HV which shows an improvement of 35% with respect to the base metal (371?HV). To improve the properties, the reinforced alloy was heat treated. The microhardness of the reinforced and aged AISI 630 was 725?HV, which was higher than the base metal by 95%. Dry sliding wear tests using a Pin-on-Disc machine were performed and it was found that the wear resistance of the reinforced surface was improved by 52% with respect to base metal. Characterisation techniques such as optical microscopy, scanning electron microscope, energy-dispersive X-ray spectrometry and XRD were used to establish morphology, structure and composition, and the presence of Mo was confirmed.     

纳米稀土氧化物对7075铝合金硬度和耐磨性的影响

对于超硬铝合金7075,本文通过加入纳米稀土氧化物来提高其硬度.在本次实验中加入纳米稀土氧化物的含量为0.2%,原铝合金7075和改性后的铝合金7075作硬度对比,结果加入纳米稀土氧化物的铝合金7075硬度较原铝合金7075提高22.4%.在干摩擦磨损测试中,加入纳米稀土氧化物的7075铝合金磨痕宽度比原铝合金7075小.     

钨含量对铝合金化学镀Ni-W-P硬度和耐磨性的影响

研究铝合金化学镀Ni-W-P三元合金的耐磨性能,探讨钨含量对铝合金（LY12）化学镀Ni-W-P耐磨性和硬度的影响。结果表明：铝合金表面化学镀Ni-W-P三元合金在400℃加热1h后,表面硬度达HV251080,表面硬度和耐磨性均较基体提高10倍以上;但过高的W含量,使得表面硬度下降。磨损实验发现,试样产生了镀层碎裂和剥落现象。其主要原因是由于铝合金基体与镀层热膨胀系数的差异及Ni3P的析出导致应力过大,引起镀层硬度和耐磨性随着W含量的增加而下降。并用化学镀Ni-W-P合金沉积机理解释了镀层成分分布特征的形成原因。     

纳米稀土氧化物对7075铝合金硬度和耐磨性的影响

对于超硬铝合金7075，本文通过加入纳米稀土氧化物来提高其硬度。在本次实验中加入纳米稀土氧化物的含量为0．2％，原铝合金7075和改性后的铝合金7075作硬度对比，结果加入纳米稀土氧化物的铝合金7075硬度较原铝合金7075提高22．4％。在干摩擦磨损测试中，加入纳米稀土氧化物的7075铝合金磨痕宽度比原铝合金7075小。     

Effect of plasma surface treatment on the structure and hardness of spherulitic iron

The microstructure of surface layers of roll-foundry iron of grade SShKhNF after plasma treatment performed with end-to-end overlapping or crossing of plasma flow tracks is studied. Dependences of the thickness and microhardness of the surface layers on the process parameters are determined. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 34–37, June, 2006.