添加稀土稳定剂的PVC异型材的喷涂性能研究

通过实验对比了添加稀土稳定剂REC-109与添加复合铅盐稳定剂德国熊牌50369的PVC异型材的喷涂性能。结果表明,随着稀土稳定剂所用的用量从2.6份增大到3.4份,氟碳涂料与添加稀土稳定剂的异型材试样表面的接触角从80.0°增大到85.0°,附着力低于复合铅盐稳定剂生产的PVC异型材,因此不适宜用于制造喷涂着色的异型材。并分析了原因,认为是由于稀土原子与PVC分子有很好的相容性,但与氟碳涂料分子相斥之故。

过程氧化对等离子喷涂Mo涂层耐磨性能的影响

利用GTV F6等离子喷枪制备Mo涂层。用SEM观察Mo涂层形貌,用XRD分析喷涂后Mo涂层的物相,用氧氮测定仪测定涂层氧含量,用干摩擦方法测定氧化物对涂层耐磨性能的影响,测定浸油环境下涂层摩擦系数。结果表明,等离子喷涂Mo涂层呈明显的层状组织,且伴有一定程度的过程氧化。过程氧化产生的Mo的氧化物弥散分布在涂层中,能够起到增大显微硬度、降低干摩擦磨损失重的作用。Mo涂层中气孔率越高,对浸油环境下的摩擦系数的影响越大。气孔率高的Mo涂层摩擦系数较小,从而减缓涂层的磨损。

适用于涂装工艺的喷涂级ABS产品研制

分析了涂装件喷涂漆膜与ABS产品之间的相互结合性能,并针对喷涂级ABS产品研制开展了系列改良实验,通过对高丙烯腈含量SAN牌号的开发和极性助剂包的改善,开发了喷涂级ABS产品。通过对喷涂级ABS产品的性能分析,证实了开发的喷涂级产品更适用于涂装件市场的生产需求。

适用于摩托车涂装件ABS产品性能分析

测试分析了3种摩托车涂装件ABS专用料与吉林石化公司生产的GE150通用ABS产品的性能。从弯曲强度、冲击强度、白度、光泽度以及丙烯腈含量等方面进行对比。并用接触角测试的方法来分析不同牌号ABS产品的涂装效果。

电弧喷涂稀土铝合金涂层在储油罐中的应用

介绍了稀土铝合金及其涂层的性能。超音速电弧喷涂稀土铝合金涂层的质量好,其孔隙率是火焰涂层的1/3～1/2倍。工业应用证明,使用超音速电弧喷涂的稀土铝合金涂层具有优良的耐湿硫化氢和Cl^-腐蚀性能,其经济效益显著,不仅可以在石油化工行业的储油罐中应用,也可以在其他储罐上推广应用。

Corrosion resistance of Fe-based amorphous metallic matrix coating fabricated by HVOF thermal spraying

The Fe-based amorphous metallic matrix coating （Fe-AMMC） was fabricated with the powder mixtures of Fe-based metallic glass synthesized with industrial raw materials, NiCr alloy and WC particle by high velocity oxy-fuel （HVOF） spraying. The corrosion resistance of Fe-AMMC was investigated by potentiodynamic polarization tests in 1 mol/L HCl, NaCl, H2SO4 and NaOH solutions, respectively. The surface morphologies corroded were observed by SEM. The results indicate that Fe-AMMC exhibits excellent corrosion resistance, higher corrosion resistance than 304L stainless steel in the chloride solutions. The low corrosion current density and passive current density of Fe-AMMC with a wide spontaneous passivation region are about 132.0μA/cm2 and 9.0 mA/cm2 in HCl solution, and about 2.5 μA/cm2 and 2.3 mA/cm2 in NaCl solution. The excellent corrosion resistance demonstrates that Fe-based amorphous metallic matrix powder is a viable engineering material in practical anti-corrosion and anti-wear coating applications.

Microstructure, mechanical and oxidation characteristics of detonation gun and HVOF sprayed MCrAlYX coatings

Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-gun sprayed MCrAlYX coating and HVOF sprayed coating, respectively. Element redistribution and formation of new phase took place during the detonation process. Besides, the porosity of D-gun sprayed coating was much lower than that of HVOF sprayed coating. On the mechanical property, the micro-hardnesses of the two coatings were in the same level (~HV 910). However, D-gun sprayed MCrAlYX coating exhibited larger standard deviation of microhardness due to its lamellar microstructure, and exhibited better bend bonding strength owing to the existence of residual compressive stress between the layers and particles. Meanwhile, due to the much more compact microstructure, D-gun sprayed MCrAlYX coating showed superior oxidation resistance to the HVOF sprayed coating. The continuous dense protective layer can form earlier in D-gun sprayed coating and thus suppress further oxidation and control the oxide thickness at a relatively low level.

Effect of TiO_2 content on properties of Al_2O_3 thermal barrier coatings by plasma spraying

Al2O3 thermal barrier coatings with different TiO2 contents were deposited on 6061 aluminum alloy by plasma spraying. The corrosion resistance, thermal insulation property and phase composition of these coatings were investigated. The results indicate that all the feedstock powders exhibit phase transformation during the spray process. With the increase of the TiO2 content in the powder, the corrosion resistance of the coating is enhanced but the thermal insulation property is decreased. This can be attributed to the higher thermal conductivity but lower melting point and brittleness of TiO2 than those of Al2O3, so it is easy for TiO2 to disperse in the brittle Al2O3 substrate during spraying, in which these dispersively distributed TiO2 play the role of hole sealing, releasing stress and reducing cracks.

Comparison between WC-10Co-4Cr and Cr_3C_2-25NiCr coatings sprayed on H13 steel by HVOF

WC?10Co?4Cr and Cr3C2?25NiCr coatings were deposited on H13 steel by high velocity oxy fuel (HVOF) spraying. To enhance the thermal stability of the WC?10Co?4Cr coating, NiCr powders were sprayed between the surface coating and substrate. The microstructures of the surface and cross section, thermal shock and wear resistance of these two coatings were investigated in detail. The carbon diffusion in the two coatings was explained from the view of the thermodynamic. And the adhesive strength of Cr3C2?25NiCr coating (64.40 MPa) is almost the same as that of WC?10Co?4Cr coating (61.69 MPa). The friction tests show that the Cr3C2?25NiCr coating has higher friction coefficient than the WC?10Co?4Cr coating at both 500 and 600 °C. The wear resistance of the Cr3C2?25NiCr coating is better than that of the WC?10Co?4Cr coating.

Microstructure and properties of nanocrystalline nickel coatings prepared by pulse jet electrodeposition

The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel.The effects of average current density on the surface morphology,microstructure,average grain size and microhardness of nickel coatings were investigated by scanning electron microscopy(SEM),X-ray diffractometry(XRD)and microhardness measurement.In addition,the corrosion resistances of coating and substrate were compared.It is revealed that the nickel coatings prepared by pulse jet electrodeposition exhibit a fine-grained structure with a smooth surface and a high density,although some pores and defects are still present in coatings.With the increase of average current density,the average grain size of nickel coatings is reduced at first and then increased.The coating with the optimum compactness,the smallest average grain size(13.7 nm)and the highest microhardness are obtained at current density of 39.8 A/dm2.The corrosion resistance is obviously increased for the coatings prepared by pulse jet electrodeposition;however,the corrosion rate is increased after a certain period due to the penetration of the corrosive media.

Effect of Al content on high temperature erosion properties of arc-sprayed FeMnCrAl/Cr_3C_2 coatings

Three types of FeMnCrAl/Cr3C2 coatings with different AI content were deposited on 20# steel substrates by the high velocity arc spraying （HVAS） process. Surface microstructures of the coatings were analyzed by optical microscopy （OM） and X-ray diffractometry （XRD）. High temperature erosion （HTE） tests were performed in an erosion tester at different impact angles. The surface morphologies of the eroded coatings were observed on a field emission scanning electron microscope（FE-SEM）. The laminated structure is found on all the prepared coatings with the porosity and oxide fraction in the coatings decreasing with the Al content from 0 to 15% （mass fraction）. Sample FA3 with 15% Al, possessing the lowest porosity and oxide fraction, has the best HTE resistance, which demonstrates that Al addition can improve the HTE resistance of the coatings. The erosion rate of sample FA1 exhibits a maximum value at 90° impact angle. The maximum erosion rates of both FA2 and FA3 samples appear in the range of 60°-90° impact angles. Erosion loss of the coatings occurs through brittle breaking, cutting and fatigue spalling.

Effect of MoSi_2 content on dielectric and mechanical properties of MoSi_2/Al_2O_3 composite coatings

Molybdenum disilicide （MoSi2） sheath and aluminum oxide （Al2O3） core blended powders were fabricated by spray drying. A derived coating material was produced for the application as microwave absorbers using the as prepared powders by atmospheric plasma spray （APS） technology. The effects of MoSi2/Al2O3 mass ratio on the dielectric and physical mechanical properties of the composite coatings were investigated. When the MoSi2 content of the composites increases from 0 to 45%, the flexure strength and fracture toughness improve from 198 to 324 MPa and 3.05 to 4.82 MPa-m1/2 then decline to 310 MPa and 4.67 MPa-m1/2, respectively. The dielectric loss tangent increases with increasing MoSi2 content, and the real part of permittivity decreases conversely over the frequency range of 8.2-12.4 GHz. These effects are due to the agglomeration of early molten MoSi2 particles and the increase of the electrical conductivity with increasing MoSi2 content.

Cavitation and electrochemical characteristics of thermal spray coating with sealing material

Steel applied in ocean environment is exposed to corrosion and cavitation and is subject to increasing damages. To prevent this, anti-corrosion thermal spray coating technique is widely used. The low-temperature thermal spray coating was performed with 85%Al-14.5%Zn-0.5%Zr for ship materials and various sealing materials were applied to improve its durability, and the electrochemical behavior and cavitation characteristics were observed. The results show that the sealing improves all the properties of the materials. Hybrid ceramic and fluoro-silicon sealing materials show good electrochemical characteristics, and the fluoro-silieon sealing material shows the best anti-cavitation characteristics.

Spray deposition of FeCrNiMn and high carbon steel coatings by thermite reaction

A novel surface cladding technique was developed to prepare the FeCrNiMn alloy and high carbon steel cladding layers,and the microhardness,bonding strength,abrasion wear and corrosion resistance were investigated.The microstructures of the cladding layers were analyzed by using X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrometry(EDS).The results show that the bonding strength between the substrate and the two cladding layers were(432.6±21)and(438.3±12)MPa,respectively.Vickers hardness values of the two cladding layers were HV418.5and HV329.6,respectively.The corrosion current densities of the two coatings were2.926×10–6and6.858×10–6A/cm2after electrochemical corrosion test in3.5%NaCl solution,and the wear rate were1.78×10–7and1.46×10–6mm3/mN after sliding wear test,respectively.This indicates that a well metallurgical bonding between the coating and the substrate was achieved,the abrasion wear and corrosion resistance of both coatings had been greatly improved compared with the substrate.The novel cladding technology is promising for preparing wear-and-corrosion resistant coatings.

Analysis of Forging Dies Coated with Tungsten Carbide through HVOF Processing

In this paper we present a performance evaluation of thermal spraying coated hot forging dies conducted in a production line. The High Velocity Oxy-Fuel process was used for the deposition of a tungsten carbide coating, which is characterized by its optimal adherence and low porosity. A metallurgical characterization of the layer was previously done, in order to obtain reference information to assist in the interpretation of the practical tests results. The coated die allowed an increase in productivity of 37.5%, besides better dimensional stability results through the process and legibility of printed numbers.

Preparation and Properties of Y_(2)O_(3)-PF Alternating Coating on Polymer Matrix Composite Material Surface

High-performance yttrium oxide-phenolic resin(Y_(2)O_(3)-PF)alternating coating was prepared on epoxy resin-based composite material using supersonic plasma spraying and dual-channel powder feeding technique.Y_(2)O_(3)-coated PF(Y_(2)O_(3)/PF)powder was firstly sprayed onto the substrate,forming a transition layer,and then the spherical Y_(2)O_(3) powder and Y_(2)O_(3)/PF powder were alternately deposited to form the composite alternating coating.Results show that the alternating coating is mainly composed of deposited Y_(2)O_(3)/PF powder.The bonding strength between coating and substrate is as high as 26.48 MPa with the single-test maximum bonding strength of 28.10 MPa,and shear strength reaches 24.30 MPa.Additionally,the heat transfer effect caused by external Y_(2)O_(3) particles gradually softens and even melts PF,thus effectively avoiding the damage of high temperature to molecular structure and thereby promoting the crosslinking and curing effects of resin during the deposition process.In the meantime,the unmelted Y_(2)O_(3) powder results in the shot peening effect,which washes out and eliminates the powder particles with inferior deposition effect,ultimately improving the physical and chemical properties of the alternating coating.

Effects of pretreatment and HVOF sprayed cermet coating on fatigue properties of TC21 titanium alloy

The effects of grit blasting (GB),shot peening (SP) pretreatment and high velocity oxygen fuel(HVOF) sprayed WC-17Co cermet coating on the fatigue properties of the novel ultra-high strength TC21 titanium alloy were investigated with a rotating bending fatigue test machine.The basic properties and surface integrity of the coating were investigated by using X-ray diffraction (XRD),surface roughness meter,microscopic hardness tester,scanning electron microscopy (SEM) and X-ray stress test instruments.The results showed that the residual compressive stress could be introduced into the surface of TC21 alloy by GB and SP pretreatment,and that HVOF sprayed WC-17Co coating was compactly bonded with TC21 alloy substrate and it significantly improved the surface hardness of the substrate.However,there was a certain residual tensile stress in the sublayer of the coating.SP could significantly increase fatigue resistance of TC21 alloy due to the surface residual compressive stress.There was no significant effect on fatigue resistance by GB treatment due to the offset between the influence of surface residual compressive stress and the surface notch effect.The fatigue resistance of TC21 alloy was significantly reduced by HVOF WC-17Co coating prepared with GB pretreatment.This could be attributed to the relaxation of surface residual compressive stress during the HVOF heating process,pore defects and residual tensile stress distribution in the WC-17Co coating with low toughness,and the surface notch induced by GB.The fatigue resistance of TC21 alloy was slightly reduced by HVOF WC-17Co coating prepared with SP pretreatment.This was attributed to the offset between the advantage effect by SP and disadvantageous effect of WC-17Co coating and high temperature factor during the HVOF process.

Experimental and Numerical Evaluation of the Performance of Supersonic Two-Stage High-Velocity Oxy-Fuel Thermal Spray (Warm Spray) Gun

The water-cooled supersonic two-stage high-velocity oxy-fuel (HVOF) thermal spray gun was developed to make a coating of temperature-sensitive material,such as titanium,on a substrate.The gun has a combustion chamber (CC) followed by a mixing chamber (MC),in which the combustion gas is mixed with the nitrogen gas at room temperature.The mixed gas is accelerated to supersonic speed through a converging-diverging (C-D) nozzle followed by a straight passage called the barrel.This paper proposes an experimental procedure to estimate the cooling rate of CC,MC and barrel separately.Then,the mathematical model is presented to predict the pressure and temperature in the MC for the specific mass flow rates of fuel,oxygen and nitrogen by assuming chemical equilibrium with water-cooling in the CC and MC,and frozen flow with constant specific heat from stagnant condition to the throat in the CC and MC.Finally,the present mathematical model was validated by comparing the calculated and measured stagnant pressures of the CC of the two-stage HVOF gun.