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在304不锈钢外圆表面激光熔覆镍基氧化锆金属陶瓷粉末,对激光工艺参数优化,制备工艺性能良好的熔覆层。研究了激光工艺参数对熔覆层宏观形貌、显微组织和硬度分布的影响。结果表明:激光功率为1.5 kW时,涂层硬度最佳;随着扫描速度的增大,熔覆层的组织有细化的趋势;通过优化扫描速度,可得到显微硬度较高,且沿熔覆层表面垂直方向的硬度分布变化不大的熔覆涂层。 相似文献
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采用预置式两步激光熔覆的方法在汽车发动机用AZ91合金表面进行了等离子喷涂+激光熔覆改性处理,通过金相、扫描电镜、XRD、硬度和极化曲线等测试手段,研究了激光熔覆Al-Si层的显微组织和耐腐蚀性能。结果表明,激光熔覆层主要由α-Al和(α-Al+β-Si)共晶组织组成;激光熔覆层的显微硬度要高于等离子喷涂层,且两种涂层的显微硬度都要高于基体合金;改性层和基体合金的耐腐蚀性能从高至低依次为:激光熔覆层>等离子喷涂层>AZ91合金。 相似文献
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在TC4钛合金表面利用激光熔覆Co基合金粉末涂层,利用扫描电镜(SEM)、能谱分析仪(EDS)和洛氏硬度计研究涂层的微观组织及力学性能。结果表明:当扫描速度固定为400 mm/s,激光功率为1.3、1.5、1.7 k W熔覆时,涂层与基体之间都实现了冶金结合。其中,激光功率为1.5 k W时熔覆效果最好,熔覆层内组织均匀致密无气孔和裂纹等缺陷。激光功率为1.3 k W时,熔覆层内出现了裂纹。当激光功率固定为1.5 k W,扫描速度为300、350、400 mm/s时,熔覆层和基体的结合情况良好,熔覆层内组织均匀致密无缺陷。随着激光功率和扫描速度的增大,涂层表面硬度呈减小的趋势,但都高于TC4基体硬度的两倍左右,表明在TC4表面激光熔覆Co基合金粉末涂层可以显著提高其硬度。 相似文献
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目的 研究激光功率对17-4PH不锈钢丝材激光熔覆组织及硬度的影响,以确定最佳激光熔覆功率,为17-4PH不锈钢丝材激光熔覆的应用提供参考.方法 在27SiMn钢活塞杆表面,对17-4PH不锈钢丝材进行了不同激光功率熔覆试验,利用金相显微镜和扫描电子显微镜表征不同激光功率熔覆层的微观组织,使用硬度计测量不同激光功率熔覆层和基体的硬度.结果 当激光功率分别为1600、1800、2000、2200 W时,熔覆层的高度由1119μm降低到1006μm,基体的穿透深度和热影响区宽度都随激光功率的增加而增大,熔覆层的组织主要为较短无方向性的板条马氏体.当激光功率为2400、3000 W时,熔覆层的高度、基体的穿透深度和热影响区宽度均随激光功率的增大而增加,最大值分别达到1119、310、638μm,熔覆层的组织主要由具有方向取向的板条马氏体组成,靠近基材的位置由晶粒细小而致密的等轴晶组成,随着激光功率的增加,熔覆层弥散析出的沉淀颗粒越来越多.此外,熔覆层和热影响区的显微硬度均高于基体,随着激光功率的增加,熔覆层的显微硬度明显增大,最高可达479.4HV0.2.结论 综合考虑激光功率对17-4PH不锈钢丝材激光熔覆组织及硬度的影响,2600 W为最佳激光熔覆功率. 相似文献
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Fe38Ni30Si16B14V2 amorphous composite coatings were fabricated by laser cladding on AISI 1045 steel in order to increase the wear resistance. The phase and microstructure of the coatings were analyzed by X-ray diffractometry and transmission electron microscopy. The wear properties of the coatings were also investigated by means of sliding wear test. The results show that the coating consists of amorphous phase in majority and nanocrystalline phase in minority. The amorphous coatings can be obtained while the scanning speed is 3 500 mm/min and the laser power is 4.8 kW. With increase of the laser power, the amorphous phase in the coating increases when it is lower than 4.8 kW. A gradient distribution of the microhardness ranges from Hv0.2 1 208 to Hv0.2 891 in the coating from top surface of the coating to the substrate. The amorphous coating is found to possess better property of wear than AISI 1045 steel substrate. 相似文献
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采用热喷涂预置和激光熔覆方法在Q235钢基体上熔覆Ni基合金涂层和Ni/WC复合涂层,研究激光功率对涂层微观结构的影响。结果表明,选择合适的激光输出功率,可获得组织分布均匀、低稀释率、与基体结合良好的合金涂层;在Ni/WC复合涂层中,合理的激光功率使WC颗粒部分熔化,并在颗粒周围重新凝固并析出针状碳化物,这既有利于提高涂层的硬度又能使未熔化的WC颗粒与涂层内合金溶剂牢固结合。激光功率较大时涂层内WC颗粒烧损并沉底,沉积在涂层底部的WC颗粒,使基体到涂层的性能发生突变,这样既容易引发裂纹及疲劳破坏,又不利于涂层表面的耐磨。 相似文献
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目的研究等离子喷涂Al-Nb_2O_5铝热体系制备的AlNbO_4-Al_2O_3-NbO_x复合涂层的组织、力学性能和摩擦磨损性能。方法以Nb_2O_5粉和Al粉为原料,通过喷雾造粒制备复合粉,采用等离子喷涂技术喷涂Al-Nb_2O_5复合粉体,利用复合粉的自反应制备出含有AlNbO_4、Al_2O_3和NbO_x的复合陶瓷涂层。利用扫描电镜、EDS和XRD检测和分析复合涂层的组织和物相。用显微硬度计测定复合涂层的硬度,并用硬度压痕法测量裂纹扩展能(Gc)。用销盘式磨损试验机测定涂层在无润滑条件下的摩擦磨损性能。结果 XRD分析可知,复合涂层由AlNbO_4、Al_2O_3和NbO_x相组成,SEM显示涂层为交替分布的层片状组织。在28~32 k W功率范围内,随着喷涂功率的升高,涂层的硬度增加,喷涂功率为32 k W时,涂层硬度最高,为912HV0.1。随着喷涂功率的升高,涂层的裂纹扩展能先升高后降低,喷涂功率为30 k W时,涂层的裂纹扩展能最大,为14.14J/m2。摩擦系数随功率的升高先降低后保持不变,28 k W时,涂层的摩擦系数为0.7~0.8,30 k W和32 k W时,涂层的摩擦系数为0.5~0.6。磨损量随喷涂功率的增加先降低后升高,喷涂功率为30 k W时,涂层的磨损量最小。磨损后的试样进行SEM检测发现有明显的犁沟、凹槽和剥落。结论涂层具有由AlNbO_4、Al_2O_3和NbO_x相组成的交替分布的多相层片状组织。喷涂功率为30 k W时,复合涂层的性能最好。复合涂层的主要磨损机制为磨粒磨损和疲劳磨损。 相似文献
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利用宽束激光在Q550钢表面制备Ni60/WC复合熔覆层,分析熔覆层显微组织、元素分布和物相组成,通过剪切试验定量表征熔覆层/基体界面结合强度,并对断口形貌进行分析阐述界面断裂机制.结果表明,熔覆层中WC颗粒部分溶解,形成了具有复杂结构的析出相,内核为M23C6碳化物(M代表Cr,W,Fe),外部为M23C6复合碳化物和γ-Ni共晶.平面晶和树枝晶在界面上生长,形成牢固冶金结合.激光功率大于2.8 kW时,熔覆层抗剪强度达到279.8 MPa以上,超过母材的75%.断口分析表明,熔覆层界面具有脆性-韧性混合断裂特征,低功率下WC颗粒在界面上沉积,削弱了界面结合强度. 相似文献
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工艺参数对高速电弧喷涂Al/1Cr13复合涂层组织结构的影响 总被引:1,自引:0,他引:1
用高速电弧喷涂制备Al/1Cr13复合涂层,采用3因素3水平正交试验法系统研究了电弧电流、电弧电压和喷涂距离对复合涂层的组织结构、孔隙率和氧含量的影响规律。采用扫描电镜对复合涂层的显微组织和孔隙率进行表征,采用氧氮含量分析仪测得涂层的氧含量。结果表明,在第9组喷涂参数即电弧电流为240A,电压为32V,喷涂距离为150mm的条件下制备的高速电弧喷涂Al/1Cr13复合涂层组织较致密,Al和1Cr13涂层的孔隙率最低分别为1.6%和2.2%。Al涂层氧含量显著低于1Cr13涂层,最低约为2%。 相似文献
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采用等离子喷涂方法,在不同喷涂距离、主气流量和喷涂功率下制备硅灰石涂层.使用扫描电镜观察了涂层的微观形貌,研究了喷涂工艺参数对涂层结构的影响.结果表明,在较大主气流量下,随着喷涂距离增加,涂层粒子扁平化程度降低,涂层内孔隙逐渐增多;在较小主气流量下,涂层粒子扁平化程度随喷涂距离增加呈现先增加后减小的趋势.主气流量增加,涂层致密,粒子扁平充分.喷涂功率增加,粒子熔化好,涂层致密;但随喷涂功率进一步增加,涂层中出现较多的圆形孔隙.喷涂工艺参数对涂层结构的影响主要通过影响熔融粒子的温度和速度所致. 相似文献
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WC-Co coating, which is a subcategory of Tungsten Carbide-based coatings, is prominent among a variety of industries. However, because of its expense, poisoning, and low corrosion resistance of Cobalt in acidic environments, alternative compositions have been designed. One of these alternatives is the Iron Aluminide intermetallic compound which can replace Cobalt. This study investigates laser cladding of WC-FeAl powder on a 321 Stainless-Steel substrate. WC-FeAl powders were synthesized by mechanical alloying of initial Aluminum and Iron powders, milled for 20 h, followed by an hour of annealing at 800 degrees Celsius. Then, the annealed particles were mechanically alloyed with WC powders for 50 h. The result of the X-ray diffraction (XRD) analysis showed that no brittle and destructive phase was formed during synthesis. Subsequently, powders were coated on the stainless-steel substrate by laser cladding method. Effect of the main parameters of the laser cladding, including laser power, laser probe velocity, and powder spray rate, on the coating properties, such as porosity, geometry, thickness and, dilution were studied. Results indicate that with a higher power of the laser, the penetration depth and the width of the coating increased. Besides, with a higher velocity of the laser probe, dilution and penetration depth decreased. Furthermore, the Higher rate of powder spray led to a thicker coating. The optimum parameters of different samples were 250 W power, 4 mm/s probe velocity, and 400 mg/s powder spray rate. Evaluation of the mechanical properties indicated that the 1600 Vickers hardness, 5.7 MPa.m1/2 fracture toughness, and 355 GPa Young's modulus were obtained. Besides, The evaluation of the mechanical properties of the coating showed that the hardness, fracture toughness, and elasticity modulus are 1600 V, 5.7 MPa.m1/2, and 355 GPa respectively. Obtained results revealed that in comparison with the WC-FeAl composite coating with 500 ppm additional Boron and WC-Co coating both fabricated by thermal spray coating, for the WC-FeAl coating studied in this investigation, respectively the hardness is 1.16 and 1.21 times higher and the fracture toughness is 2.5 and 2.8 times higher. As well, Young's modulus of the coating was 1.56 times higher than the WC-Co coating made by the laser cladding method. 相似文献
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The formation of a TiN-Ti composite coating by thermal spraying of titanium powder with laser processing of the subsequent
coating in a low-pressure N2 atmosphere was examined. A low-pressure plasma spray system was used in combination with a CO2 laser. First, the coating was plasma sprayed onto a mild steel substrate using a N2 plasma jet and titanium powder in a controlled low-pressure N2 atmosphere. The coating was then irradiated with a CO2 laser beam in a N2 atmosphere, and the coating was heated with a N2 plasma jet. The amount of TiN formed in the coating was characterized by X-ray diffraction analysis. The influence of plasma
spraying conditions such as plasma power, flow of plasma operating gases, chamber pressure, and laser irradiating conditions
on the formation of TiN was investigated. The effect of TiN formation in the titanium coating on Vickers hardness of the coatings
was examined. It was evident that coating hardness increased with an increase in TiN content in the coating and that a TiN-Ti
composite coating with a hardness of more than 1200 H V can be obtained with the use of laser irradiation processing. 相似文献
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针对激光熔覆高熵合金涂层的成分设计已有较多探究,但激光工艺参数对涂层结构与性能的影响尚缺乏系统研究。采用激光熔覆技术在316L不锈钢基体表面制备Fe Co Ni Cr高熵合金涂层,系统探究激光功率(1.2~2.0 kW)对Fe Co Ni Cr高熵合金涂层的组织结构以及耐腐蚀性能的影响规律。不同激光功率制备的Fe Co Ni Cr涂层均由典型的单一面心立方结构(FCC)组成,但随着激光功率的增大,涂层逐渐出现择优取向。Fe Co Ni Cr涂层呈现典型的双层组织结构特征,底部为柱状晶,顶部为等轴晶,但随着激光功率增加,顶部等轴晶逐渐向柱状晶转变。随着激光功率的增加,Fe Co Ni Cr涂层混合熵值逐渐下降。Fe Co Ni Cr涂层具有优异的耐腐蚀性能,但随激光功率的增加而逐渐减弱。其中,当功率为1.2 kW时,涂层的自腐蚀电流密度最小,自腐蚀电压最大且涂层表面无腐蚀坑,具有最佳的耐腐蚀性能,优于316L基体以及Stellite6和Ni60等常规激光熔覆涂层。通过优化激光功率获得具有良好耐腐蚀性能的激光熔覆Fe Co Ni Cr高熵合金涂层,可对该类涂层的开发、制备和应用提供一定的理论指导和技术支持。 相似文献