热喷涂制备铝基复合材料涂层及其热处理工艺

为了提高铝基涂层的硬度和耐磨性,研制了两种新型复合材料涂层.采用可控气氛等离子喷涂的方法制备了不同比例的铝-氧化铝、铝-铝青铜复合材料,通过扫描电子显微镜观察复合材料的组织形貌并进行成分分析,测定了其显微硬度.再对制得的复合材料涂层进行再结晶热处理,再次进行组织形貌观察和相分析,并进行显微硬度测试.结果表明：当铝和氧化铝比例为4∶3,铝和铝青铜比例为1∶3,热处理温度在350℃时,所得到的复合材料涂层的组织分布均匀,晶粒细小.     

电弧喷涂制备铝基非晶纳米晶合金材料

采用高速电弧喷涂技术,制备了铝基非晶纳米晶复合涂层材料.经XRD、TEM分析发现,铝基非晶纳米晶复合涂层是由非晶相、纳米晶相和晶化相共同组成的;涂层呈明显层状结构,层与层之间结合良好;涂层结构致密,无明显裂纹和孔隙,孔隙率约为1.8%;涂层的平均显微硬度值约为311 HV100,已达到传统制备工艺获得的铝基非晶合金的显微硬度值.     

电弧喷涂铝涂层的抗氧化应用

铝涂层可以显著地降低钢铁工件高温环境下的氧化趋势．电弧喷涂工艺是获得铝涂层的有效方法之一．电弧喷涂铝涂层在不经预先扩散热处理的条件下，可以在喷涂状态下直接用于高温．研究了某些因素，例如，铝涂层厚度、加热温度、加热保护涂料以及铝涂层的热稳定性等对渗铝层形成的影响．     

TiAl合金电弧喷涂Al涂层的高温氧化性能

为了提升TiAl合金的高温抗氧化能力,采用电弧喷涂工艺在TiAl合金表面制备了纯铝涂层,并分别在900℃和1 000℃进行了恒温氧化试验.通过绘制氧化动力学曲线,对比了有无涂层试样的抗氧化性能.运用SEM、EDS、EPMA和XRD分析其氧化前后涂层的微观形貌、成分组成、元素分布和相组成.结果表明：纯铝涂层均匀致密、无裂纹.在900℃空气中氧化100 h后,涂层表面形成了致密的Al₂O₃氧化膜,次表层为TiAl₃相,扩散层为TiAl₂相.在1 000℃空气中氧化100 h后,涂层表面氧化膜由Al₂O₃和少量TiO₂组成,次表层为TiAl₃相,扩散层为TiAl₂相.电弧喷涂铝涂层提高了TiAl合金的高温抗氧化能力.     

电弧喷涂层经历不同热过程后的行为

本文论述了电弧喷涂的Cr13钢、铝青铜及二者的伪合金在较高的温度环境下不受损坏的原理。当工件是平板状而且温度过高时(例如900℃),存在涂层边缘挠起的危险。喷涂于外圆的铝青铜涂层可以承受5次900℃的热冲击而无损坏迹象。Cr13钢涂层不能承受这种热冲击。 加热使涂层中的铝与铬向基体中扩散。它会增强涂层与基体的结合。这种扩散区是孤立的。因而结合强度的提高也是有限的。     

电弧喷涂与电铸相结合的模具制造方法

为了解决电弧喷涂锌铝合金制造而成的模具表面硬度低、不耐磨损等问题,需要在锌铝合金表面进行镀层的处理,即通过电镀在模具表面进行铜镀层的制备.通过扫描电子显微镜对锌铝合金涂层和铜镀层进行了孔隙和夹杂物的观察,并测试了锌铝合金喷涂层和铜镀层的显微硬度,对喷涂层和电镀层进行了结合强度的测试.结果表明：通过对锌铝合金模具表面进行镀层处理,消除了模具表面缺陷,使模具的硬度、表面强度、表面光洁度和耐蚀能力都有很大的提高.     

TA1表面制备Ni/Al涂层的反应扩渗及抗氧化行为

为了提高纯钛的高温抗氧化性能,采用电弧喷涂和等离子喷涂方法在纯钛表面制备Ni/Al涂层.对试件进行900 ℃×5 h热处理后,再进行900 ℃×40 h连续氧化实验,探索其高温抗氧化行为.结果表明,经过表面改性处理的Ni/Al涂层可以显著提高纯钛的高温抗氧化性.在热处理过程中Ni/Al涂层中的Al发生熔化扩散并与Ni和Ti形成以NiAl与TiAl₃相为主的扩散层.在氧化过程中Ni/Al涂层表面形成连续且致密的α-Al₂O₃,同时表面扩散层中的富铝相可为涂层表面提供充足的Al元素,进而对纯钛基体提供有效的高温抗氧化保护作用.     

TA1表面制备Ni/Al涂层的反应扩渗及抗氧化行为

为了提高纯钛的高温抗氧化性能,采用电弧喷涂和等离子喷涂方法在纯钛表面制备Ni/Al涂层.对试件进行900℃×5 h热处理后,再进行900℃×40 h连续氧化实验,探索其高温抗氧化行为.结果表明,经过表面改性处理的Ni/Al涂层可以显著提高纯钛的高温抗氧化性.在热处理过程中Ni/Al涂层中的Al发生熔化扩散并与Ni和Ti形成以NiAl与TiAl_3相为主的扩散层.在氧化过程中Ni/Al涂层表面形成连续且致密的α-Al_2O_3,同时表面扩散层中的富铝相可为涂层表面提供充足的Al元素,进而对纯钛基体提供有效的高温抗氧化保护作用.     

零部件表面电弧喷涂研究

研究了钢制汽车零部件表面电弧喷涂铝涂层的工艺、设备及涂层的性能,并和目前广泛采用的火焰喷涂铝方法进行了性能及经济性对比.结果表明:电弧喷涂涂层致密、孔隙率低,与基体结合良好,能耗少,效率高.     

铝线材喷涂工艺及涂层性能

在钢基体上分别采用电弧线材喷涂和火焰线材喷涂两种工艺制备铝涂层，并对两种涂层的硬度、孔隙率、结合强度、耐蚀性能和磨损性能及机理进行了试验研究和对比分析。     

AZ91D镁合金表面等离子喷涂Al_2O_3-TiO_2陶瓷涂层的微观组织及防护性能

采用大气等离子喷涂技术在AZ91D镁合金表面制备Al2O3-TiO2陶瓷涂层。对涂层的显微组织、化学成分、相组成及显微硬度进行表征,并对涂层的耐磨损和耐电化学腐蚀防护性能进行研究。结果表明,Al2O3-TiO2陶瓷涂层的组织呈现层状结构,主要组成相为α-Al2O3、γ-Al2O3和金红石TiO2。涂层平均硬度654.2HV,涂层具有良好的抗磨损和抗电化学腐蚀防护性能。     

铈对铝铜合金—Al_2O_3颗粒复合材料界面的影响

本文探讨了铈对铝铜合金—Al_2O_3颗粒复合材料界面的影响。结果表明,适量铈可以改善铝铜合金与Al_2O_3间的润湿性能,提高界面结合强度。但未发现界面反应相,界面仍属于直接结合类型。凝固过程中,颗粒与凝固相界面相互作用的结果,导致颗粒大多分布于胞晶或树枝晶间,未发现铈对Al_2O_3颗粒的这种分布状态产生显著影响     

Influence of potential on structure and properties of microarc oxidation coating on Mg alloy

In order to obtain optimizing microarc oxidation coating on Mg alloy from a friendly-enviormental electrolyte free of Cr6 and PO43-, constant potential regime was applied to produce it. The influence of potential on the morphology, composition, structure and other properties, such as microhardness and corrosion resistance were investigated by scanning electron microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD), hardness tester and electrochemical method. The results clearly show that oxidation potential plays an important role in the formation of coating's structure and properties. The microarc oxidation coating is smooth and white, which consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, its content of Al and Si increases with the increasing operated potential. While the inner layer is compact and the content of Al and Si are lower than that of the external layer. The coating is composed of several phases and the major phases are MgA12O4 and MgO, and the minor phases are Al2O3 and SiO2 when the potential is higher. The microhardness of coating is obtained the maximum at the potential of 45 V, so does the corrosion resistance.     

Fe-Al系粉末压坯激光反应烧结的研究

探讨了Fe Al系粉末压坯在激光作用下的反应烧结行为、物相转变、微观结构和硬度特征。结果表明:在短暂的烧结过程中,粉末压坯实现了燃烧和蔓延,完成了单元素组分向产物相的转变,富Al相大多在颗粒边界形成,也有部分是在颗粒内部析出;随Al含量的增多,边界上析出相的Al含量比内部析出的多,试样的硬度值提高。     

可控气氛喷涂钛涂层及涂层电化学性能

为了研究在低度真空环境中所获得的钛涂层的组织和性能,以氩气为载气,在压力为0.4MPa、载气温度为室温、不同的喷涂条件下,用热喷涂方法在Q235钢基体上制备了钛金属涂层.经扫描电子显微镜（SEM）观察,发现在真空中用氩气为载气喷涂的钛涂层组织致密,缺陷与孔隙相对较少.x 射线衍射分析仪（XRD）分析表明,在空气中喷涂的钛涂层有较多的氧化物和氮化物;在真空中喷涂的钛涂层基本上没有氧化物和氮化物,其衍射图谱与纯钛十分接近;在空气中用氩气为载气喷涂的钛涂层含有一些氧化物,涂层中的缺陷和孔隙数量介于前两种状态之间.采用动电位极化法研究了在不同条件下热喷涂钛涂层的电化学腐蚀行为,并与纯钛试样进行比较.结果表明：在真空条件下喷涂的钛涂层腐蚀电位高于在空气中喷涂的钛涂层和在空气中用氩气为载气喷涂的钛涂层,但略低于纯钛的腐蚀电位.     

Effect of electric field on the activity and quenching structure of liquid Cu-Al alloys

The activity coefficient of A1 in molten Cu decreases with the increasing of electric current applied to the liquid alloy of Cu-0.2wt%Al. To investigate the mechanism, the quenching experimental results of the liquid A1-Cu alloy show that there is a remarkable change in structure, in which the solute congregates along the current direction especially for DC current. The mechanism of the activity coefficient change of A1 in molten Cu-0.2wt%Al alloy treated by electrical field was discussed. Further, the results also provide an evidence for the short-range-ordered liquid metal.     

Preparation and properties of the Ni-Al/Fe-Al intermetallics composite coating produced by plasma cladding

A novel approach to produce an intermetallic composite coating was put forward.The microstructure,microhardness,and dry-sliding wear behavior of the composite coating were investigated using X-ray diffraction (XRD),scanning electron microscopy (SEM),energy dispersive spectrum (EDS) analysis,microhardness test,and ball-on-disc wear experiment.XRD results indicate that some new phases FeAl,Fe0.23Ni0.77Al,and Ni3Al exit in the composite coating with the Al2O3 addition.SEM results show that the coating is bonde...     

Influence of potential on structure and properties of microarc oxidation coating on Mg alloy

In order to obtain optimizing microarc oxidation coating on Mg alloy from a friendly-enviormental electrolyte free of Cr⁶⁺ and PO ₄ ³⁻ , constant potential regime was applied to produce it. The influence of potential on the morphology, composition, structure and other properties, such as microhardness and corrosion resistance were investigated by scanning electron microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD), hardness tester and electrochemical method. The results clearly show that oxidation potential plays an important role in the formation of coating’s structure and properties. The microarc oxidation coating is smooth and white, which consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, its content of Al and Si increases with the increasing operated potential. While the inner layer is compact and the content of Al and Si are lower than that of the external layer. The coating is composed of several phases and the major phases are MgAl₂O₄ and MgO, and the minor phases are Al₂O₃ and SiO₂ when the potential is higher. The microhardness of coating is obtained the maximum at the potential of 45 V, so does the corrosion resistance.     

Microstructure and wear resistance of in situ NbC particles reinforced Ni-based alloy composite coating by laser cladding

The in situ synthesized NbC particles reinforced Ni-based alloy composite coating was produced by laser cladding a precursor mixture of Ni-based alloy powder,graphite and niobium powders on a steel substrate.The microstructure,phase composition and wear property of the composite coating were investigated by means of scanning electron microscopy(SEM),X-ray diffraction(XRD)and dry sliding wear test.The experiment results show that the composite coating is homogeneous and free from cracks,and about 0.8 mm thick.The microstructure of the composite coating is mainly composed of NbC particles,CrB type chromium borides,γ-Ni primary dendrites,and interdendritic eutectics.CrB phases often nucleate and grow on the surface of NbC particles or in their close vicinity.NbC particles are formed via in situ reaction between niobium and graphite in the molten pool during the laser cladding process and they are commonly precipitated in three kinds of morphologies,such as quadrangle,cluster,and flower-like shape.Compared with the pure Ni-based alloy coating,the microhardness of the composite coating is increased about 38%,giving a high average hardness of HV0.21000,and the wear rate of the composite coating is decreased by about 32%,respectively.These are attributed to the presence of in situ synthesized NbC particles and their well distribution in the coating.     

合金法制备镍超微粉

研究了以高熔点金属钨和制备超微粉用金属镍的合金为原料，为直流电弧等离子体法在０．１ＭＰａ的Ｈ２＋Ａｒ混合气氛中连续制备镍超微粉的方法，结果表明，以钨－镍合金为原料时镍超微粉地产率比用纯镍为原料时的高一部以上，并且捕集的超微粉中几乎不含有金属钨。