共查询到20条相似文献,搜索用时 156 毫秒
1.
采用拉拔的方法制备了火焰喷涂用 Al-6Si 丝材, 研究了中间退火和成品退火温度对铝硅合金性能的影响,
并对铝硅合金丝材涂层性能进行研究, 对退火后铝硅合金坯料抗拉强度和伸长率进行测试, 对退火后的成品铝硅
合金丝金相组织进行了分析表征, 并对自制 Al-6Si 丝材和进口铝硅丝材 (Metco SF Aluminum) 涂层的孔隙率、 显
微硬度、 结合强度及热震性能进行分析比较。 结果表明, 铝硅合金坯料采用 450 ℃退火工艺显著改善了力学性能,
铝硅合金丝材经 400 ℃退火处理, 晶粒均匀。 采用自制 Al-6Si 丝材和进口铝硅丝材喷涂涂层孔隙率、 显微硬度、
结合强度及热震等性能基本相当, 满足封严涂层应用要求。 相似文献
2.
3.
钼系涂层的制备工艺研究 总被引:5,自引:1,他引:4
严淑群 《金属材料与冶金工程》2001,(2):16-19,30
本研究经钼粉为基本材料,对大气等离子喷涂技术制备钼纱涂层的工艺参数、组织性能及使用效果进行了深入研究、分析,与传统丝材喷涂方法制备钼涂层相比,成本大幅降低,涂层性能及工艺稳定性显著提高。 相似文献
4.
Xing-Hai Tan ;Jian-Ming Xu ;Qiong Li ;Guan-Jun Yang ;Yu-Yue Wang ;Cheng-Xin Li ;Chang-Jiu Li ;黄凌峰 ;王志伟 《热喷涂技术》2014,(4):59-65
陶瓷颗粒增强型金属基复合涂层在诸多工业领域都有需求,其中包括炼钢工业。本文中,MCr Al Y-Al2O3复合粉末通过球磨法制备,并且通过等离子喷涂、超音速火焰喷涂和冷喷涂分别制备了MCr Al Y-Al2O3复合涂层。实验结果显示,可以选用不优先使基体与Al2O3结合的复合粉末控制涂层中的Al2O3含量。涂层粉末的微结构在冷喷涂涂层和超音速火焰喷涂涂层中得到了良好的保留,这是因为喷涂粒子未熔化或部分熔化。然而,对于等离子喷涂的涂层,大多数Al2O3颗粒被隔离在层状界面,在条状界面上形成连续的氧化皮。经退火处理后,由元素扩散引起的条状界面的强化使得超音速火焰喷涂和大气等离子喷涂的涂层硬度增大。此外,冷喷涂涂层由于退火后加工硬化效果的消除,硬度增加不像超音速火焰喷涂和等离子喷涂涂层那样明显。 相似文献
5.
6.
本文介绍了一种从粘结层到面层成分和性质逐渐不同的功能梯度涂层(FGC).在涂层制备过程中,使用了混合喷嘴,采用双丝喷涂工艺.为了提高涂层与基体的结合力,首先在基体上喷涂金属丝材作为粘结层,为提高涂层的耐磨性,又将粉末状的硬质材料喷射到含有大量的熔融丝材的火焰中制备出面层涂层.结果表明,功能梯度涂层是由纯金属部分和含有硬... 相似文献
7.
为解决钛合金表面直接进行电镀涂层制备结合力较低的问题,本文采用超音速火焰喷涂技术在钛合金叶尖表面制备了不同厚度 NiCoCrAlY 底层,并在底层表面用复合电镀技术制备了 Ni-cBN 耐磨面层。研究表明NiCoCrAlY-Ni-cBN 耐磨涂层的组织结构良好,结合强度大于 74.2 MPa,能够在 600 ℃大气环境中长时间保持组织和结构稳定。NiCoCrAlY-Ni-cBN 钛合金叶尖涂层与 NiCrFe/Al/hBN 封严涂层的对磨匹配效果良好,可以为钛
合金叶尖提供良好的对磨防护。 相似文献
8.
9.
超音速火焰喷涂制备Cr2AlC涂层组织性能研究 总被引:2,自引:0,他引:2
采用真空分段烧结法制备了两种不同粒度的高单相Cr2AlC化合物粉末,并使用超音速火焰喷涂(HVOF)方法在GH4169高温镍合金上制备了Cr2AlC涂层,对喷涂粉末及涂层进行了相结构分析,测试了涂层的显微硬度、孔隙率,并采用扫描电子显微镜(SEM)对喷涂粉末及涂层截面形貌进行了观察,结合扫描电镜能谱仪(EDS)和X射线衍射研究了涂层相组成,分析了粉末粒度对涂层微观组织结构的影响。研究结果表明:采用超音速火焰喷涂成功制备了厚度超过200μm的Cr2AlC涂层,涂层与基体紧密结合,涂层微观组织致密,采用较细的粉末有利于得到更高致密度的涂层。在喷涂过程中,有少量Cr2AlC粉末发生分解形成Cr7C3化合物。 相似文献
10.
电弧丝材喷涂技术的研究 总被引:3,自引:0,他引:3
研制出了PW送丝机构,对电弧丝材喷涂的工艺参数及涂层的组织性能进行了研究实验,讨论了工艺参数与组织性能间的相应关系,并对电弧喷涂锌铝涂层和研制的长城7号涂层的实际应用情况作了介绍. 相似文献
11.
采用火焰喷涂方法制备镍/石墨可磨耗封严涂层。通过调整工艺参数制备硬度适中的镍石墨涂层,并对涂层的结合强度、热冲击以及微观结构等进行研究。试验发现,镍石墨可磨耗封严涂层结合强度、热冲击等性能均能满足使用要求。 相似文献
12.
AbstractThe diameter of droplets in electric arc wire spraying is critical in determining the microstructure, porosity and oxide content of the resulting sprayed coatings. Droplet diameter controls dynamic and thermal behaviour in the spray, and the splashing and spreading behaviour of droplets at deposition. In electric arc wire spraying, the droplet diameter is determined by a combination of the melting behaviour of the feedstock wires in a direct current arc, combined with primary and secondary atomisation processes under the action of a high velocity atomising gas. The high frequency arc voltage variations during electric arc spraying of Fe-0·8C have been investigated and arc voltage fluctuations related to atomisation events occurring at the wire tips during spraying. A simple analytical model has been proposed which allows the diameter of primary droplets produced by atomisation to be calculated from the wire feedrate and the average time period for material removal, which was obtained from the voltage traces. Primary droplets were then assumed to undergo secondary atomisation according to correlations from the literature, and resulting droplet diameters were compared with diameters measured by experiment. Despite uncertainties in some of the thermophysical data and dynamic conditions during atomisation, predicted droplet diameters were in good agreement with experimental mass mean droplet diameters obtained under a range of atomising gas pressures, arc voltages and wire feedrates. 相似文献
13.
14.
Niraj Bala Harpreet Singh Satya Prakash 《Metallurgical and Materials Transactions A》2011,42(11):3399-3416
Microstructure and mechanical properties of cold-spray coatings are usually required in order to explore the potential industrial
application of the latter. This article demonstrates the successful formulation of Ni-20Cr and Ni-50Cr coatings on two boiler
steels, namely, SAE 213-T22 and SA 516 steel by cold-spray process. The microstructure, coating thickness, phase formation,
and microhardness properties of the coatings were evaluated. The coatings were subjected to cyclic heating and cooling cycles
at an elevated temperature of 1173.15 K (900 °C) to ascertain their high-temperature oxidation behavior. Moreover, these cyclic
exposures can give useful information regarding the adhesion of the coatings with the substrate steels. Of all the coatings,
the Ni-50Cr coating on SA 516 steel had a maximum average hardness value of 469 Hv. As observed from the surface field emission–scanning
electron microscopy (FE-SEM) analysis, the coatings were found to have nearly dense microstructure with the sprayed particles
in interlocked positions. It was concluded that the cold-spray process is suitable for spraying the preceding powders onto
the given boiler steels to produce nearly dense and low oxide coatings. The coatings, in general, were found to follow the
parabolic rate of oxidation and were successful in maintaining their surface contact with their respective substrate steels. 相似文献
15.
Gagandeep Kaushal Niraj Bala Narinder Kaur Harpreet Singh Satya Prakash 《Metallurgical and Materials Transactions A》2014,45(1):395-410
To protect materials from surface degradations such as wear, corrosion, and thermal flux, a wide variety of materials can be deposited on the materials by several spraying processes. This paper examines and compares the microstructure and high-temperature corrosion of Ni-20Cr coatings deposited on T22 boiler steel by high velocity oxy-fuel (HVOF), detonation gun spray, and cold spraying techniques. The coatings’ microstructural features were characterized by means of XRD and FE-SEM/EDS analyses. Based upon the results of mass gain, XRD, and FE-SEM/EDS analyses it may be concluded that the Ni-20Cr coating sprayed by all the three techniques was effective in reducing the corrosion rate of the steel. Among the three coatings, D-gun spray coating proved to be better than HVOF-spray and cold-spray coatings. 相似文献
16.
Jianhong He Enrique J. Lavernia Yourong Liu Yunfei Qiao Traugott E. Fischer 《Metallurgical and Materials Transactions A》2002,33(1):145-157
Near-nanostructured WC-18 pct Co coatings, with low amounts of non-WC carbide phases, have been synthesized using high velocity
oxygen fuel (HVOF) thermal spraying under spraying conditions of varying fuel chemistry, fuel-oxygen ratio, and powder particle
size. The results show that the temperature the particles experience during spraying depends on the preceding parameters.
Compared to available published results on WC-Co system coatings, nanostructured WC-18 pct Co coatings, synthesized in these
experiments, contain very low amounts of non-WC carbide phase (less than 10 pct vol). This is comparable to that of the conventional
WC-12 pct Co coating, prepared in the present study for comparison purposes. Regardless of whether the binder phase in the
agglomerated feedstock powder particles melt or not, the WC particles do not appear to experience significant growth as a
result of the spraying. The size of WC particles remains in the 200 to 500 nm range, consistent with that present in the feedstock
powder. The as-received near-nanostructured WC-18 pct Co feedstock powder exhibits morphological characteristics that lead
to low amounts of non-WC carbide phases in the coatings. The microstructure and phase constitution of the coatings depend
on particle size of the feedstock powder and flame characteristics of the fuels during spraying. A higher particle temperature
causes more decomposition of the WC phase but reduces porosity in the coatings, this occurs with higher flame temperature
and smaller particle sizes. Propylene fuel produces less decomposition of the WC phase despite the higher flame temperature
and, thus, provides the best combination of dense coating with low amount of non-WC phase. 相似文献
17.
18.
Effect of thermal spray on the microstructure and adhesive strength of high-velocity oxy-fuel-sprayed Ni-Cr coatings on 9Cr-1Mo steel 总被引:1,自引:0,他引:1
Coatings of 80Ni-20Cr and 50Ni-50Cr on a 9Cr-1Mo steel substrate were produced by high-velocity oxy-fuel (HVOF) spraying to
protect the steel against steam oxidation in ultrasupercritical (USC) boilers. The oxidation studies on the coated specimens
showed good protection against the scale growth on the steel substrate. Both the 80Ni-20Cr and 50Ni-50Cr coatings formed a
thin protective oxide film on the coating surface. The 80Ni-20Cr coating showed Fe diffusion from the substrate to the coating
and nickel diffusion from the coating to the substrate during the oxidation process. In the case of 50Ni-50Cr coatings, the
diffusion process was reduced, but a continuous layer of chromium carbide was observed at the coating/substrate interface
during the oxidation. The adhesive/cohesive strength of these coatings was evaluated on aged specimens at 750 °C by using
a simple tensile test. The results of the as-coated 80Ni-20Cr specimens showed an adhesive-strength value of 68 MPa. On extended
aging, the strength of the coating increased beyond the detection limit of the resin. The nickel diffusion from the coating
to the substrate and the iron diffusion from the substrate to the coating caused the increased adhesive strength. In the case
of 50Ni-50Cr, the as-coated specimens showed an average adhesive strength of 76 MPa and showed a decreasing trend on the aged
specimens. The formation of chromium carbide at the interface caused inferior values in the adhesive/cohesive strength of
the 50Ni-50Cr coatings. The chromium carbide formed on the coating/substrate interface was identified as M23C6-type carbide. 相似文献
19.
20.
采用等离子喷涂物理气相沉积 ( PS-PVD ) 技术开展了热障涂层梯度结构调控研究,通过调整喷涂送粉速率,
在底部、中间和顶部沉积阶段制备了五种不同的热障涂层,对热障涂层的显微组织、粗糙度、孔隙率、耐熔盐腐
蚀和耐粒子冲蚀性能进行表征,阐明了显微结构变化对热障涂层耐侵蚀性能的影响。研究表明:送粉速率的变化
对PS-PVD热障涂层羽柱状结构的沉积有显著的影响,低送粉速率下,涂层底部结构比较致密,当送粉速率增大时,
由于粉末颗粒在喷涂过程气化不充分,未熔粒子增加,羽柱状顶部结构趋向致密结构转变,涂层顶部孔隙率下降,
表面粗糙度降低。送粉速率由底至顶梯度递增制备的涂层表现出较高的耐熔盐腐蚀性能和耐粒子冲蚀性能。 相似文献