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1.
高速火焰电弧(HVAF-ARC)复合喷涂枪是高速火焰喷涂枪和电弧喷涂枪的结合体,利用产生的高速燃气来雾化加速电弧喷涂过程中产生的熔融粒子,提高了喷涂粒子的飞行速度,降低了粒子的氧化,可高效制备优质的涂层。文中利用自主开发的新型高速火焰电弧复合喷涂枪和普通高速电弧喷涂枪,分别在钢基体上制备了3Cr13涂层,通过对涂层的性能检测发现,复合喷涂枪所制备涂层的氧元素含量和孔隙率都比普通高速电弧喷涂枪制备的涂层低,分别降低了33%和49%,硬度提高了12%,复合喷涂枪制备涂层的性能得到较大的提高。 相似文献
2.
Mechanical and thermomechanical properties of metal spray invar for composite forming tooling 总被引:1,自引:0,他引:1
The subject of this paper is the assessment of the thermal and mechanical properties of Invar steel coatings, deposited using
electric arc spraying, and the correlation of these properties to the spray parameters and processes used to offer coatings
with characteristics appropriate to the requirements of tools used in the fabrication of precision polymer matrix composite
work pieces. In particular, two processing methods, inert and air atomization, and three arc spray gun configurations (air
cap design) were evaluated. The low coefficient of thermal expansion (CTE) properties of Invar are maintained in the spray-deposited
coatings using both high velocity oxy-fuel (HVOF) and air-atomized arc spraying, although HVOF coatings have significantly
lower CTE and greater durability than those deposited by arc spraying. The mechanical properties of the coatings are low compared
to bulk Invar, regardless of the spray parameters and hardware used. Inert arc spraying affords more consistent coating characteristics
but this comes with a compromised durability. The spray hardware was found to be more significant in determining the coating
properties than the parameters employed. 相似文献
3.
Plasma-sprayed coatings of Ni-18.5Cr-6Al, molybdenum, and A1-12Si are used in selected applica-tions for dimensional restoration
of jet engine hardware. These coatings are usually limited, how-ever, by the thickness to which they can be applied. In order
to increase the coating thickness capability of these materials, the dual-wire electric arc process was investigated. This
paper presents the results of a testing program to characterize the bond strengths, microstructure, hardness, and surface
roughness of these three types of materials using a standard dual-wire electric arc spray sys-tem and a high-velocity (arc
jet) spray gun. A comparison of bond strengths and microstructure to typical equivalent (in composition) plasma spray coatings
was also made. The test program was de-signed to emulate, as closely as possible, substrate materials, spray application procedures,
and coat-ing thicknesses that would be used in service. 相似文献
4.
铝基非晶纳米晶复合涂层的喷涂工艺 总被引:1,自引:0,他引:1
为了研究喷涂参数对涂层性能的影响规律,采用高速电弧喷涂技术制备铝基非晶纳米晶复合涂层,利用正交试验法系统研究喷涂电流、喷涂电压、喷涂距离、喷枪移动速度和雾化空气压力对涂层性能的影响规律。优化后的工艺参数为喷涂电流160 A,喷涂电压36 V,喷涂距离200 mm,喷枪移动速度300 mm/s,雾化空气压力0.7 MPa,喷涂参数对涂层性能影响的主次顺序为:雾化空气压力、喷涂电压、喷枪移动速度、喷涂电流和喷涂距离。采用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)和透射电镜(TEM)对工艺优化后的涂层进行分析,同时对涂层的显微硬度和孔隙率进行了测试。结果表明,采用优化参数制备的涂层组织结构致密,孔隙率为1.13%,硬度可达392 HV0.1,涂层具有明显的非晶纳米晶相,非晶含量约为24.2%。 相似文献
5.
Thermal spray processes such as plasma spraying and HVOF have gained markets due to a steady process of development of materials
and equipment. One disadvantage of thermal spray processes is that costs must be competitive compared to techniques such as
PTA and electroplating. In order to reduce costs, the more economical spray processes like conventional wire flame spraying,
as well as arc spraying, are becoming more popular. There are modern arc spray gun designs on the market that meet the requirements
of modern coating properties, for example aviation overhaul applications as well as the processing of cored wires. Nevertheless,
the physical basis of arc spraying is well known. The aim of the present investigation is to show how the influence of spray
velocity (not particle velocity) affects coating structure with respect to arc spray parameters. 相似文献
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8.
Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco
AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of
PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years.
In comparison to conventional vacuum plasma spraying (VPS) or low pressure plasma spraying (LPPS), the new proposed process
uses a high energy plasma gun operated at a reduced work pressure of 0.1 kPa (1 mbar). Owing to the high energy plasma and
further reduced work pressure, PS-PVD is able to deposit a coating not only by melting the feed stock material which builds
up a layer from liquid splats but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between
the conventional physical vapor deposition (PVD) technologies and standard thermal spray processes. The possibility to vaporize
feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties
of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In
contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Owing to the forced
gas stream of the plasma jet, complex shaped parts such as multi-airfoil turbine vanes can be coated with columnar thermal
barrier coatings using PS-PVD. Even shadowed areas and areas which are not in the line of sight of the coating source can
be coated homogeneously. This article reports on the progress made by Sulzer Metco in developing a thermal spray process to
produce coatings out of the vapor phase. Columnar thermal barrier coatings made of Yttria-stabilized Zircona (YSZ) are optimized
to serve in a turbine engine. This process includes not only preferable coating properties such as strain tolerance and erosion
resistance but also the simultaneous coverage of multiple air foils. 相似文献
9.
Thermal barrier coatings (TBC) are an effective engineering solution for the improvement of in service performance of gas turbines and diesel engine components. The quality and further performance of TBC, likewise all thermally sprayed coatings or any other kind of coating, is strongly dependent on the adhesion between the coating and the substrate as well as the adhesion (or cohesion) between the metallic bond coat and the ceramic top coat layer. The debonding of the ceramic layer or of the bond coat layer will lead to the collapse of the overall thermal barrier system. Though several possible problems can occur in coating application as residual stresses, local or net defects (like pores and cracks), one could say that a satisfactory adhesion is the first and intrinsic need for a good coating. The coating adhesion is also dependent on the pair substrate-coating materials, substrate cleaning and blasting, coating application process, coating application parameters and environmental conditions. In this work, the general characteristics and adhesion properties of thermal barrier coatings (TBCs) having bond coats applied using High Velocity Oxygen Fuel (HVOF) thermal spraying and plasma sprayed ceramic top coats are studied. By using HVOF technique to apply the bond coats, high adherence and high corrosion resistance are expected. Furthermore, due to the characteristics of the spraying process, compressive stresses should be induced to the substrate. The compressive stresses are opposed to the tensile stresses that are typical of coatings applied by plasma spraying and eventually cause delamination of the coating in operational conditions. The evaluation of properties includes the studies of morphology, microstructure, microhardness and adhesive/cohesive resistance. From the obtained results it can be said that the main failure location is in the bond coat/ceramic interface corresponding to the lowest adhesion values. 相似文献
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采用等离子喷涂铝粉作为打底材料在碳纤维增强聚酰亚胺复合材料(PMC)基体上制备了Al2O3和ZrO2轻质陶瓷防护涂层,测试了涂层的剪切结合强度、耐热循环性能、抗冲蚀性能、隔热性能。结果表明,等离子喷涂铝粉作打底层的涂层系统,性能优于电弧喷铝或电弧喷锌作打底层的涂层系统。带有Al2O3涂层的试样失重不到基体材料失重的1/3,Al2O3和ZrO2陶瓷涂层都可以为聚酰亚胺复合材料基体提供有效的冲蚀防护。Al2O3和ZrO2陶瓷涂层都可以为聚酰亚胺复合材料基体提供有效的隔热防护,ZrO2涂层隔热性能优于Al2O3涂层。 相似文献
12.
Plasma spray—physical vapor deposition (PS-PVD) is a low pressure plasma spray technology to deposit coatings out of the vapor phase. PS-PVD is a part of the family of new hybrid processes recently developed by Sulzer Metco AG (Switzerland) on the basis of the well-established low pressure plasma spraying (LPPS) technology. Included in this new process family are plasma spray—chemical vapor deposition (PS-CVD) and plasma spray—thin film (PS-TF) processes. In comparison to conventional vacuum plasma spraying and LPPS, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and EB-PVD coatings. This paper reports on the progress made at Sulzer Metco to develop functional coatings build up from vapor phase of oxide ceramics and metals. 相似文献
13.
Tailoring powder characteristics to suit the plasma spray process can alleviate difficulties associated with the preparation
of hydroxyapatite (HA) coatings. Commercial HA feedstock normally exhibit an angular morphology and a wide particle size range
that present difficulties in powder transport from the powder hopper to the plasma spray gun and in nonuniform melting of
the powders in the plasma flame. Hence, combustion flame spheroidized hydroxyapatite (SHA) was used as the feedstock for plasma
spraying. Spherical particles within a narrow particle size range are found to be more effective for the plasma spray processes.
Results show coatings generated from spheroidized HA powders have unique surface and microstructure characteristics. Scanning
electron microscope (SEM) observation of the coating surface revealed well-formed splats that spread and flatten into disc
configurations with no disintegration, reflecting adequate melting of the HA in the plasma and subsequent deposition consistency.
The surface topography is generally flat with good overlapping of subsequent spreading droplets. Porosity in the form of macropores
is substantially reduced. The cross-section microstructure reveals a dense coating comprised of randomly stacked lamellae.
The tensile bond strengths of the SHA coatings, phase composition, and characteristics of the coatings generated with different
particle sizes (125 to 75 μm, 45 to 75 μm, 20 to 45 μm, and 5 to 20 μm) showed that a high bond strength of ∼16 MPa can be
obtained with SHA in the size range from 20 to 45 μm. This can be improved further by a postspray treatment by hot isostatic
pressing (HIP). However, larger particle size ranges exhibited higher degrees of crystallinity and relatively higher HA content
among the various calcium phosphate phases found in the coatings. 相似文献
14.
为了提高高温合金材料的高温抗氧化性,利用爆炸喷涂工艺制备了MCrAlY Al2O3金属陶瓷涂层.比较了采用压缩空气和N2作为保护气体对涂层性能的影响,利用扫描电子显微镜(SEM)、显微硬度计对涂层性能进行了分析,在此基础上,进一步研究了涂层的结合强度,并对涂层的高温抗氧化性能进行了测试.结果表明:采用N2作为保护气体,涂层均匀致密,孔隙率小,显微硬度合格;涂层与基体的结合强度达到了95MPa,涂层具有良好的抗氧化性能. 相似文献
15.
纯铜SHS反应热喷涂Al2O3基复合陶瓷涂层的性能研究 总被引:1,自引:0,他引:1
采用SHS(自蔓延高温合成)反应火焰喷涂工艺,将Al-CuO铝热反应体系引入到喷涂陶瓷材料中,在纯铜表面制备Al2O3基复合陶瓷涂层.结果表明,SHS反应热喷涂层与基体的结合好于常规热喷涂,辅以Ni-Al合金打底,复合涂层500度下热震循环40次时仍完好无损.复合涂层的XRD图谱表明,在层间及涂层内部生成的NiCu及AlxCuy化合物有助于增强涂层的性能,同时Al的适当过量可以起到弥补喷涂过程中Al的损失并为体系提供良好的液相环境的作用,提高反应转化率,降低孔隙率,同时复合涂层具有较好的耐磨性及抗氧化性. 相似文献
16.
Carlos R. Fadragas E. V. Morales J. A. Muñoz I. S. Bott C. A. Lariot Sánchez 《Journal of Thermal Spray Technology》2011,20(6):1183-1191
A Cu-Al alloy has been used as bond coat between a carbon steel substrate and a final coating deposit obtained by applying
the twin wire electric arc spraying coating technique. The presence of a copper-based material in the composite system can
change the overall temperature profile during deposition because copper exhibits a thermal conductivity several times higher
than that of the normally recommended bond coat materials (such as nickel-aluminum alloys or nickel-chromium alloys). The
microstructures of 420 and 304 stainless steels deposited by the electric arc spray process have been investigated, focusing
attention on the deposit homogeneity, porosity, lamellar structure, and microhardness. The nature of the local temperature
gradient during deposition can strongly influence the formation of the final coating deposit. This study presents a preliminary
study, undertaken to investigate the changes in the temperature profile which occur when a Cu-Al alloy is used as bond coat,
and the possible consequences of these changes on the microstructure and adhesion of the final coating deposit. The influence
of the thickness of the bond layer on the top coating temperature has also been also evaluated. 相似文献
17.
This paper presents what is our actual knowledge about sensors, used in the harsh environment of spray booths, to improve
the reproducibility and reliability of coatings sprayed with hot or cold gases. First are described, with their limitations
and precisions, the different sensors following the in-flight hot particle parameters (trajectories, temperatures, velocities,
sizes, and shapes). A few comments are also made about techniques, still under developments in laboratories, to improve our
understanding of coating formation such as plasma jet temperature measurements in non-symmetrical conditions, hot gases heat
flux, particles flattening and splats formation, particles evaporation. Then are described the illumination techniques by
laser flash of either cold particles (those injected in hot gases, or in cold spray gun) or liquid injected into hot gases
(suspensions or solutions). The possibilities they open to determine the flux and velocities of cold particles or visualize
liquid penetration in the core of hot gases are discussed. Afterwards are presented sensors to follow, when spraying hot particles,
substrate and coating temperature evolution, and the stress development within coatings during the spray process as well as
the coating thickness. The different uses of these sensors are then described with successively: (i) Measurements limited
to particle trajectories, velocities, temperatures, and sizes in different spray conditions: plasma (including transient conditions
due to arc root fluctuations in d.c. plasma jets), HVOF, wire arc, cold spray. Afterwards are discussed how such sensor data
can be used to achieve a better understanding of the different spray processes, compare experiments to calculations and improve
the reproducibility and reliability of the spray conditions. (ii) Coatings monitoring through in-flight measurements coupled
with those devoted to coatings formation. This is achieved by either maintaining at their set point both in-flight and certain
spray parameters (spray pattern, coating temperature…), or defining a good working area through factorial design, or using
artificial intelligence based on artificial neural network (ANN) to predict particle in-flight characteristics and coating
structural attributes from the knowledge of processing parameters. 相似文献
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19.
Y. Tsunekawa M. Okumiya T. Kobayashi M. Okuda M. Fukumoto 《Journal of Thermal Spray Technology》1996,5(2):139-144
Nitrides of transition metals have good wear- and corrosion-resistant properties because of their high hardness and chemical
stability. Chromium-nitride coatings can be deposited by ion plating; however, the thin thickness due to the slow deposition
rate must be improved for severe wear-resistant applications. The main objective in this paper is to realize good structural
control in the processing of chromiumnitride in situ composite coatings formed at a high deposition rate. They were synthesized
by reactive low-pressure plasma spraying using elemental chromium powder as a spray material. The transferred arc between
the gun electrode and the substrate was used to accelerate the nitriding reaction. The sprayed coatings consist of chromium,
Cr2N, and CrN, which have a composition gradient from the substrate interface to the surface. The volume fraction of Cr2N increases with transferred arc current, and nonreacted chromium concurrently decreases, except close to the substrate. The
CrN phase, however, only exists as a surface layer of 20 to 30 μm because it is decomposed to Cr2N above 1420 K. The hardness of the composite coatings depends on the volume fraction of Cr2N, and it increases to 1300 HV at a Cr2N volume fraction of 0.98. The seizure stress with lubricant depends on the coating hardness. The maximum seizure stress of
24.9 MPa is obtained at a hardness of 1300 HV. The composite coatings also show a superior wear resistance. Hence, the Cr2N in situ composite coatings synthesized by reactive plasma spraying with transferred arc are expected to be good candidates
for wear-resistant applications. 相似文献
20.
新型高速电弧喷涂枪的开发研究 总被引:54,自引:13,他引:41
详细介绍了开发研制的新型高速电弧喷涂枪:分析测定了新型喷枪和普通喷枪出口的雾化气流速度,同时采用A1和3Cr13作为对比试验材料,对涂层进行性能研究并观察了其组织结构。结果表明:新型喷枪的雾化气流速度的捌试计算值在距枪口80mm的范围内仍然能保持在600m/s左右,比普通喷枪的雾化气流速度有显著地提高:高速电弧喷滁熔融的金属粒子雾化充分,涂层组织致密,层状结构十分明显,并且结合强度值和硬度值均较高:新型高速电弧喷涂枪,结构简单,工作性能稳定。高速电弧喷涂是一种优质、高效、低成本的热喷涂方法。 相似文献