等离子束表面冶金技术研究及其进展

等离子束表面冶金是一种新的表面涂层技术。本文综述了等离子束表面冶金设备、专用粉末设计、涂层的组织性能、熔池结晶特点以及应用方面的研究进展,并展望了等离子束表面冶金的发展方向。     

等离子束表面强化技术的研究进展

对等离子束表层合金化技术与激光技术特点和经济性进行了比较,综述了等离子束表面强化技术的基本原理、表面冶金技术、工艺方法和研究进展。与常规CO2激光技术相比等离子束表层合金化技术在技术上、涂层质量上、工艺适应性、生产成本上具有较明显的优势。对等离子束合金化的应用前景进行了展望。     

等离子束表面冶金制备铁基梯度涂层的研究

利用等离子束表面冶金技术在45号钢基体上制备梯度涂层,探讨了等离子束表面冶金制备铁基梯度涂层的冶金过程,详细分析了等离子束表面冶金熔池的凝固机理、凝固特征对凝固组织的影响。采用金相显微镜、X射线衍射仪、扫描电镜研究了涂层的组织,利用显微硬度计测试了涂层的显微硬度。结果表明,合金涂层组织主要由γ-Fe,M7C3和TiC组成;涂层的显微硬度可达到800HV0.2。从基体到表面,涂层的成分、组织和显微硬度呈现出平缓梯度变化,消除了成分突变和应力集中的影响。因此涂层具有无晶体缺陷,内韧外硬的特性。     

稀土元素对等离子束表面冶金涂层组织和性能的影响

采用直流放电压缩电弧等离子束表面冶金技术，在Q235钢表面制备了添加La2O3和CeO2的铁基合金涂层。研究了稀土对等离子束表面冶金涂层的组织和性能的影响。结果表明，添加适量的稀土氧化物可有效改善冶金层的组织和性能，减少其中的裂纹与气孔，提高显微硬度和韧性。     

送粉等离子束表面冶金工艺及涂层强韧化机制研究

利用自行研发的送粉等离子束表面冶金涂层设备及Fe-Cr-Ni-B-Si-C系混合合金粉末在普通低碳钢表面制备了铁基复合材料涂层.采用OM、SEM、EDS、XRD等手段,研究了同步送粉等离子束表面冶金工艺参数对涂层显微组织的影响及涂层的强韧化机制.结果表明,工作电流、扫描速度以及搭接工艺是影响涂层微观组织特征的重要因素.经工艺优化后的复合材料涂层的典型微观组织由固溶了大量Cr、少量Ni、Si的极度过饱和的γ相枝晶及枝晶间复杂合金碳硼化物 γ相共晶组织构成.细晶强化、固溶强化和高硬度相的沉淀析出及其弥散强化是等离子束表面冶金复合材料涂层强韧化的3种主要机制.     

等离子束表面冶金Al2Cu和α-Al复合涂层研究

采用等离子束表面冶金技术,以纯铝为基材,纯铜粉末为冶金原料,在铝表面制得了冶金结合良好的Al2Cu和α-Al复合涂层.涂层组织具有快速凝固组织特征,涂层底部为逆热流方向长大的粗大枝晶,上部为细小枝晶和大胞晶均匀分布.涂层最高硬度为260HV,较铝基材的硬度(74.5HV)有显著提高,在油润滑滚动磨损试验条件下纯铝的磨损量是涂层的6～10倍,说明涂层具有优异的耐磨性和载荷特性.     

等离子束表面冶金过程中熔体流动对凝固组织的影响

等离子束表面冶金技术是以等离子弧为热源，采用同步送粉方式，在基体材料表面获得一层均匀致密、结合牢固的冶金涂层，是一种极有发展前途的金属表面改性处理新技术。研究表明在等离子表面冶金中金属熔体流动存在很大的温度梯度以及气流的吹力、等离子束的冲击力和电磁力的搅拌作用，这种流动特征对凝固组织和冶金层成分产生很大的影响，对优化等离子束表面冶金工艺具有重要指导意义。     

工艺参数对等离子束表面冶金铁基涂层组织及性能的影响

采用等离子束表面冶金技术，在Q235钢表面制备了铁基合金涂层。试验研究了等离子束表面冶金工艺参数（如工作电流、扫描速度等）对冶金层的影响。结果表明，工艺参数对冶金层显微组织及显微硬度有很大的影响。在保证涂层与基体形成良好的冶金结合的前提下，适当增大扫描速度或减小工作电流有利于涂层组织的细化。     

大面积等离子束表面冶金铁基涂层的成形机理及组织结构

采用等离子束表面冶金技术,通过多道搭接方式在低碳钢基体上制备大面积铁基复合超厚涂层。基于大面积涂层成形的特点,探讨搭接率与涂层厚度等的变化规律,并利用扫描电镜、X射线衍射仪、金相显微镜、显微硬度计及磨损试验分析测试了涂层的相组成、组织及性能。结果表明:表面冶金涂层厚度可达3.0 mm,无裂纹、气孔等缺陷;组织为γ-(Fe,Ni)枝晶、M23C6、CrB及原位合成的TiC陶瓷颗粒,与基体呈良好的冶金结合。由于颗粒强化、细晶强化和弥散强化等多种强化作用,大面积Fe基超厚涂层具有良好的耐磨性能。     

截齿等离子束表面冶金铁基耐磨涂层研究

采用等离子束表面冶金技术，在采煤机截齿磨损严重的部位制备了与基材呈冶金结合的铁基复合涂层。利用光学显微镜、扫描电镜、X衍射仪和显微硬度计等手段分析了冶金涂层组织，测试了涂层的显微硬度和磨损性能。结果表明：涂层主要由γ-（Fe，Ni）和（Cr，Fe）7（C，B）3相组成，在固溶强化、弥散强化和细晶体强化共同作用下，冶金涂层具有较高的显微硬度和较好的耐磨性能。     

Study on Fe-Based Coating Produced by Plasma Surface Metallurgy

THE PLASMA SURFACE METALLURGY has greatdevelopment potential,whose principle is that thesurface of metal melts relying upon energy ofDC-Plasma-Jet and molten or semi-molten alloypowder or ceramic powder is sent into arc stream andmolten bath.With shifting of plasma arc stream,thealloy molten bath promptly solidifies and the coatingbonds with the substrate metallurgically.TheDC-Plasma-Jet possesses large energy density,hightemperatures over10000K and large efficiency ofenergy trans…     

新型双层辉光等离子表面冶金高速钢及其锯切工具

主要介绍了双层辉光等离子表面冶金技术在普通低碳钢或低合金钢表面形成的等离子表面冶金高速钢及其在手用锯条方面的应用和产业化。以技术、工艺、设备为主线,全面总结和阐述了等离子表面冶金高速钢锯条产业化的过程及艰难历程,对我国发展原创性技术及其产业化也提出了一些意见和建议。     

Surface modification of polymer fibre by the new atmospheric pressure cold plasma jet

A new cold plasma jet has been developed for surface modification of materials at atmospheric pressure. This new cold plasma jet generator is composed of two concentric cylindrical all-metal tube electrodes. The argon is fed into the inner-grounded electrode, the outer electrode is connected to the high-voltage power supply and covered with a layer of dielectric, and then a stable cold plasma jet is formed and blown out into air. The plasma gas temperature is only 25–30 °C. Preliminary results are presented on the modification of polypropylene (PP) and polyethylene terephthalate (PET) fibres by this cold plasma jet. The water contact angle of these materials is found to decrease after plasma treatment and it will recover a little in two months. The chemical changes on the surface of polymers are studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) is used to study the changes in surface feature of polymers due to plasma treatment. The hydrophilicity and surface structure of these materials after plasma treatment are discussed. The results show that such a plasma jet is effective.     

冷等离子体射流中微细电火花加工特性研究

采用晶体管脉冲电源,在氧气辅助氮气等离子体射流、氮氧混合等离子体射流及外部压缩空气辅助氮气等离子体射流等不同冷等离子体介质中进行了微细电火花加工特性的实验研究,以期确定加工过程稳定的工艺条件,达到提高加工效率和加工质量的目的。在氧气辅助氮气等离子体射流实验中发现,随着氧气流量的增加,材料去除速度和表面粗糙度值均有增大趋势;采用压缩空气辅助氮气等离子体射流的电火花加工在表面质量、边缘质量方面均优于氧气辅助氮气等离子体射流加工。     

Influence of pore size on penetration of surface modification into woven fabric treated with atmospheric pressure plasma jet

One of the biggest difference between atmospheric pressure plasma jet (APPJ) and other plasma surface treatment is that only one side (top) of substrate is contacted with plasma jet at atmospheric pressure while in other plasmas two sides (top and bottom) of substrate are both contacted with plasma. The modification of the bottom side of woven fabric treated by APPJ is largely dependent on the penetration of active species in plasma jet, which is accordingly affected by plasma parameters and the structure of materials. In order to investigate the influence of pore size on penetration of surface modification into woven fabric treated with APPJ, four kinds of polyester woven fabrics with different pore sizes were used as the model porous medium. Two groups of parallel polyester fibers are respectively and tightly pasted on the top and bottom side of each fabric. Penetration of plasma effects through the pores was detected by changes in contact angle on the bottom side before and after APPJ treatment. It was further demonstrated by changes in surface morphology and chemical composition using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) analyses. The degree of penetration of APPJ surface modification was increased with the increasing pore size. Complete penetration was realized in fabric with pore size larger than 200 μm and nearly no penetration was found in fabric with the pore size smaller than 10 μm. This is attributed to more active species in plasma jet diffusing through the larger pores in fabric. Those species can reach the bottom side without losing their modifying ability during the movement process. Therefore the pore size might be a more important factor affecting penetration of APPJ surface modification into woven fabric.     

层流等离子体射流铝合金表面熔覆层中颗粒分布

采用层流等离子体射流在ZL104铝合金表面制备SiCp／Al-Si复合材料熔覆层。结果表明，熔覆层中SiCp颗粒与基体结合良好，但在熔覆层上颗粒分布不均匀，而且多数分布在枝状晶界上。通过提高层流等离子体射流扫描速度，可以显著提高SiCp颗粒在熔覆层中的均匀性。     

Penetration depth of atmospheric pressure plasma surface modification into multiple layers of polyester fabrics

Penetration depth of plasma surface modification of polyester fabrics was investigated. An eight-layer stack of woven polyester fabrics was exposed to a helium/oxygen atmospheric pressure plasma jet. Water-absorption time was used to evaluate surface hydrophilicity on the top and the bottom sides of each fabric layer and water capillary rise height was recorded as a measure of modification effectiveness for each fabric layer. Surface morphology and chemical compositions of each fabric layer in the stack were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). After atmospheric pressure plasma jet treatment, the top side of the polyester fabric became more hydrophilic. The penetration of plasma surface modification into the fabric layers was deeper for fabrics with larger average pore sizes. It was found that helium/oxygen atmospheric pressure plasma jet was able to penetrate 8 layers of polyester fabrics with pore sizes of 200 μm.