喷涂Al/SiC复合材料的制备与组织分析

采用等离子喷涂技术和亚音速火焰喷涂技术制备了高性能Al/SiC复合材料.利用OM,SEM,TEM,XRD等仪器详细分析了上述两种技术制备的Al/SiC复合材料微观组织.结果显示,亚音速火焰喷涂技术和等离子喷涂技术均可制备出SiC体积分数大于50%的Al/SiC复合材料,所制备的Al/SiC复合材料组织致密、颗粒均匀分布、SiC颗粒和Al之间的界面结合良好.XRD研究表明,等离子喷涂Al/SiC复合材料中存在着Al,SiC,晶体Si等相.亚音速火焰喷涂Al/SiC复合材料中的相是由Al,SiC和少量的Al2O3组成.与等离子喷涂相比,亚音速火焰喷涂Al/SiC复合材料的孔隙率较高,氧化程度较高.此外等离子喷涂Al/SiC复合材料中有一定量纳米尺度的晶粒和颗粒.     

热压对喷涂SiCp/Al复合材料组织和热性能的影响

为了将SiCp／Al复合材料应用到电子封装领域,利用亚音速火焰喷涂技术制备了SiCp／Al复合材料,探讨了热压处理对喷涂SiCp／Al复合材料组织及热性能的影响。结果表明,体积分数和孔隙率是影响喷涂SiCp／Al复合材料热性能的主要因素。热压处理可以有效地降低喷涂SiCp／Al复合材料内部的孔隙率,使复合材料的组织更加致密、均匀、界面结合更加牢固。与喷涂态相比较,热压处理后SiCp／Al复合材料热导率和热膨胀系数均有所提高。     

亚音速火焰喷涂层与等离子喷涂层耐磨性的对比

利用亚音速火焰喷涂和等离子喷涂分别制备Fe-WC金属陶瓷涂层,对两种喷涂层的耐磨性进行了研究.结果表明,在耐磨性试验过程中等离子喷涂层的磨损失重变化比亚音速火焰喷涂层磨损失重变化稳定,等离子喷涂层的耐磨性明显高于火焰喷涂层的耐磨性.     

反应等离子喷涂制备FeAl2O4-A12O3-Fe复合涂层的研究

以铝粉和氧化铁粉为原料，制备出适于等离子喷涂的复合团聚粉体；并采用反应等离子喷涂技术制备出FeAl2O4-A12O3-Fe复合涂层，用SEM和XRD分析了复合涂层的组织结构。结果表明：反应等离子喷涂得到了以层状基体相FeAl2O4与硬质相Al2O3为骨架，球状Fe相弥散分布于基体上的复合涂层。     

冷喷涂SiC/Al纳米复合涂层的组织结构与性能

为制备基体相晶粒细小、增强相均匀分布的SiC/Al纳米复合涂层,以Al、SiC为原料,采用高能球磨法获得SiC颗粒弥散分布的纳米晶Al基复合材料粉末,利用冷喷涂技术低温成型制备了SiC/Al纳米复合涂层,分析了SiC含量对复合涂层相结构、晶粒尺寸、微观结构、硬度及磨损性能的影响规律。结果表明：冷喷涂可实现球磨纳米晶复合粉末结构的原位移植,所制备SiC/Al纳米复合涂层组织致密,微米及亚微米级SiC弥散分布在纳米晶Al（约80 nm）基体之上;SiC颗粒对Al基体有明显强化作用,冷喷涂SiC/Al纳米复合涂层的硬度随SiC体积分数的增加而显著增加,50% SiC/Al纳米复合涂层的硬度高达515 HV_0.3,约为Al块材的13倍;冷喷涂SiC/Al纳米复合涂层的耐磨损性能随着SiC含量增加而显著提高,涂层磨损失效机制为磨粒对基体的切削犁沟变形。     

CuCrZr合金表面亚音速与超音速等离子喷涂NiAl涂层的组织结构与结合强度

分别用亚音速和超音速等离子喷涂方法在CuCrZr合金表面制备了NiAl涂层,通过正交试验对工艺参数进行优化,测定了涂层与基体的结合强度。利用SEM、EDS、XRD等设备研究了涂层的组织结构、物相变化及涂层与基体间的结合方式。结果表明,超音速等离子喷涂制备的NiAl涂层粒子变形充分、组织致密,涂层与基体间的结合强度明显高于亚音速喷涂层;两种方法制备的涂层与基体的界面处均主要为Al,界面的局部区域Cu-Al发生反应生成了Cu₃Al₂、CuAl₂、CuAl等新相,形成了1～3 µm宽的“微冶金结合”层。     

高速火焰喷涂Fe-25Al/11SiC复合涂层性能研究

用高速火焰喷涂方法制备出Fe-25Al／11SiC复合涂层，对涂层的结合强度、抗热震性及温度为650℃时的热腐蚀行为进行研究，并利用扫描电镜和X射线衍射仪（XRD）对腐蚀前后涂层的表面形貌和相组成进行分析。结果表明：Fe-25Al／11SiC复合涂层组织致密，与基体结合状况良好，且以机械结合为主；该涂层具有较好的抗热震性能；经过150h热腐蚀后，Fe-25Al／11SiC复合涂层腐蚀增重约为基体20钢的1／3，抗热腐蚀性能优异；Fe-25Al／11SiC复合涂层发生的是第二类低温热腐蚀。     

等离子喷涂与超音速火焰喷涂NiCr-Cr3C2涂层组织与摩擦磨损性能研究

目的 研究等离子喷涂与超音速火焰喷涂NiCr-Cr3C2涂层的组织、力学性能和摩擦磨损性能。方法 采用等离子喷涂与超音速火焰喷涂工艺制备NiCr-Cr3C2涂层,并采用X射线衍射仪（XRD）、扫描电镜（SEM）、万能试验机、显微硬度计和高速往复摩擦磨损试验机,系统地分析了两种工艺所得涂层的物相、组织、结合强度、硬度及摩擦磨损性能。结果 两种工艺制备的NiCr-Cr3C2涂层与基体界面结合效果良好。等离子喷涂NiCr-Cr3C2涂层为层片状组织,层间可见微裂纹,孔隙率较高;超音速火焰喷涂NiCr-Cr3C2涂层组织均匀,无明显微裂纹,可见少量微小孔隙。物相分析表明,等离子喷涂涂层由NiCr、Cr3C2和Cr7C3相组成,而超音速火焰喷涂涂层由NiCr和Cr3C2相组成。超音速火焰喷涂NiCr-Cr3C2涂层的耐磨性优于等离子喷涂涂层,等离子喷涂涂层和超音速火焰喷涂涂层的稳态摩擦系数分别为0.4和0.6。随载荷升高,两种工艺制备的NiCr-Cr3C2涂层摩擦系数均显著下降。磨损后,等离子喷涂NiCr-Cr3C2涂层表面具有明显的凹痕和剥落,而超音速火焰喷涂NiCr-Cr3C2涂层磨痕表面较光滑,未见明显剥落。两种工艺制备的涂层磨损机制均为磨粒磨损和疲劳磨损。结论 超音速火焰喷涂NiCr-Cr3C2涂层较等离子喷涂涂层组织更为致密,具有更为优良的综合力学性能和耐磨性,等离子喷涂制备的NiCr-Cr3C2涂层的减摩性较好。     

反应等离子喷涂制备FeAl2O4-Al2O3-Fe复合涂层的研究

以铝粉和氧化铁粉为原料,制备出适于等离子喷涂的复合团聚粉体;并采用反应等离子喷涂技术制备出FeAl2O4-Al2O3-Fe复合涂层,用SEM和XRD分析了复合涂层的组织结构.结果表明反应等离子喷涂得到了以层状基体相FeAl2O4与硬质相Al2O3为骨架,球状Fe相弥散分布于基体上的复合涂层.     

反应等离子喷涂合成Fe-FeAl2O4-Al2O3复合涂层的研究

利用机械团聚法制备了适合等离子喷涂的Fe2O3／Al复合粉体，将此粉体送入等离子焰流，通过复合粉的自反应制备含有Fe、Al2O3和FeAl2O4的复合陶瓷涂层。利用扫描电镜（SEM）、X射线衍射仪（XRD）和透射电镜（TEM）等检测手段对反应等离子制备的复合涂层进行了研究。结果表明：涂层具有以层状陶瓷为骨架，球形金属为弥散相的组织，反应生成涂层的过程是分步进行的，由于反应生成的部分纳米颗粒以及金属的存在，使得涂层的耐磨性和韧性比普通Al2O3涂层有了较大的提高，尤其在高载荷作用下，复合涂层的耐磨性比普通Al2O3提高近两倍。     

Microstructure characteristics of SiC particle-reinforced aluminum matrix composites by plasma spraying

Aluminum with 55 and 75 vol.% SiC powders were ball milled as plasma spray feedstock. The feedstock was deposited onto a graphite substrate to form a freestanding composite by air plasma spraying. The microstructure characteristics of the sprayed composite were investigated by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The SiC volume fraction and porosity in the sprayed composites depend on plasma spray conditions. The silicon phase was formed in the sprayed composites in some plasma spray conditions, and its amount was related to the input of electrical power into the plasma spray. The mechanism of silicon formation was studied. In the sprayed composites, no reaction products could be observed in the Al/SiC interface. Impurity materials from ball media, stainless steel, and ZrO₂ reacted with aluminum and silicon to form complex compounds during plasma spray deposition.     

Microstructure Characteristics of SiC Particle-Reinforced Aluminum Matrix Composites Coatings by Cold Spraying

A dense Al/SiCp composite coating with high volume fraction(60%)of nano SiCp reinforcement was fabricated by cold spraying of ball-milled Al-60SiCp composite powder.The morphologies evolution of the Al-60SiCp composite powder during ball milling and the microstructure and microhardness of the cold-sprayed Al-60SiCp composite coating were investigated.The results show that Al particles undergone fracture deformation and nano SiC particles are uniformly distributed in soft Al matrix after ball milling.A dense Al-60SiCp composite coating can be fabricated by cold spraying of ball milled composite powder.Nano SiC particles in the cold-sprayed Al-60SiCp composites coating exhibit a reasonably uniform distribution.The Hv0.5 microhardness of the Al-60SiCp composite coating is reached up to(5.30±0.53)GPa due to the enhancement of SiC particles,compared to(0.34±0.03)GPa for the pure Al bulk.     

Adhesion, hardness and structure of thermal sprayed Al/SiC composite coat on graphite

Combustion powder spraying has been used in the coating of graphite by a layer of Al and SiC composite utilizing the Box-Wilson design that fixes the optimum spraying parameters of Al/SiC wt.% composition, substrate temperature and spraying distance. Graphite substrate surface was conditioned by subjecting to sand blast roughing and nitrogen flushed furnace treating. Under the spraying conditions considered, a single spraying pass attains a coating layer 65 ± 15 µm of average thickness. Two optimum spraying conditions that concern adhesion of coating to graphite and its hardness are obtained. Upon spraying for adhesion purpose, the coat/graphite adhesion strength is found to depend mainly on graphite surface conditioning, but for hardness purpose, it is found to depend mainly on SiC wt.% composition.Microstructure of transversal coating section indicates that adhesion efficiency is due to physical interlocking of molten sprayed materials on the roughened and treated graphite surface. Phases identified from fractured coatings by XRD analysis show individual phase of Al, SiC and graphite in addition to small amount of new extra phases that combine the three constituents such as Al₄C₃ and Al₄Si₂C₅. These phases play a role with the good physical interlocking in achieving adhesion strength that exceeds that of graphite.     

Aluminum-silicon carbide coatings by plasma spraying

An aluminum base composite (Al-SiC) powder has been developed for producing plasma sprayed coatings on Al and other metallic substrates. The composite powders were prepared by mechanical alloying of 6061 Al alloy with SiC particles. The concentration of SiC was varied between 20 and 75 vol%, and the size of the reinforcement was varied from 8 to 37 μm in the Al-50 vol% SiC composites. The 44 to 140 μm composite powders were sprayed using an axial feed plasma torch. Adhesion strength of the coatings to their substrates were found to decrease with increasing SiC content and with decreasing SiC particle sizes. The increase in the SiC content and decrease in particle size improved the erosive wear resistance of the coatings. The abrasive wear resistance was found to improve with the increase in SiC particle size and with the SiC content in the composite coatings.     

Hydroxyapatite coatings for biomedical applications deposited by different thermal spray techniques

Thermally sprayed hydroxyapatite (HAp) coatings are widely used for various biomedical applications due to the fact that HAp is a bioactive, osteoconductive material capable of forming a direct and firm biological fixation with surrounding bone tissue.Bioceramic coatings based on nanoscale HAp suspension and microscale HAp powder were thermally sprayed on Ti plates by high-velocity suspension flame spraying (HVSFS) technique and atmospheric plasma spraying (APS) as well as high velocity oxy fuel spraying (HVOF) technique. HVSFS is a novel thermal spray process developed at IMTCCC, for direct processing of submicron and nano-sized particles dispersed in a liquid feedstock.The deposited coatings were mechanically characterized including surface roughness, micro hardness and coating porosity. The bond strength of the layer composites were analyzed by the pull-off method and compared for the different spray techniques. Phase content and crystallinity of the coatings were evaluated using X-ray diffraction (XRD). The coating composite specimen and initial feedstock were further analysed by scanning electron microscope (SEM) and rheology analysis.     

Difference in particle characteristics and coating properties between spraying metallic and ceramic powder cored wires

The sprayed particles of metallic and cermet wires were collected to analyze the atomization state of the particles in arc spraying forming, the microstructure and properties of metallic and ceramic coatings were investigated and compared. Particle size analyzer was used for quantifying particle size. The XRD, SEM and optical microscope（OM） were used to analyze the phase composition and microstructure of the particles and coatings. From the experimental results, some difference of particle characteristics was established between the spraying metallic and ceramic cored wires, and the microstructure and properties of coatings depend strongly on the particles behaviors. The result shows that Fe-TiB2/Al2O3 composite coating has a high potential for abrasive wear applications.     

超音速大气等离子喷涂TiB2−SiC涂层的制备与性能

将喷雾造粒制备的TiB2?SiC粉末进行真空煅烧,采用超音速大气等离子喷涂制备TiB2?SiC涂层,研究喷涂功率和喷涂距离对TiB2?SiC涂层性能的影响,并对超音速等离子喷涂制备TiB2?SiC涂层的工艺进行优化.结果表明:煅烧后的喷涂粉末粒径分布均匀,球形度良好,流动性增强.煅烧粉末制备的涂层结构致密、沉积效率高....     

纳米结构Ni/Al2O3热喷涂喂料的制备及显微分析

采用化学包覆、喷雾造粒以及气体保护烧结等工艺,制备了纳米结构Ni/Al2O3热喷涂喂料.对喂料以及使用该喂料制备的等离子喷涂涂层的显微结构进行了分析,结果表明:化学包覆后,Ni/Al2 O3粒度约为100～200 nm,喂料为多孔的球形结构,直径约为20～50 μm.采用该喂料制备的涂层表面粗糙度约为50μm,内部呈现...