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1.
Fabrication and Properties of Plasma-Sprayed Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/ZrO<Subscript>2</Subscript> Composite Coatings 总被引:1,自引:0,他引:1
N. Dejang A. Limpichaipanit A. Watcharapasorn S. Wirojanupatump P. Niranatlumpong S. Jiansirisomboon 《Journal of Thermal Spray Technology》2011,20(6):1259-1268
Al2O3
/xZrO2 (where x = 0, 3, 13, and 20 wt.%) composite coatings were deposited onto mild steel substrates by atmospheric plasma spraying of mixed
α-Al2O3 and nano-sized monoclinic-ZrO2 powders. Microstructural investigation showed that the coatings comprised well-separated Al2O3 and ZrO2 lamellae, pores, and partially molten particles. The coating comprised mainly of metastable γ-Al2O3 and tetragonal-ZrO2 with trace of original α-Al2O3 and monoclinic-ZrO2 phases. The effect of ZrO2 addition on the properties of coatings were investigated in terms of microhardness, fracture toughness, and wear behavior.
It was found that ZrO2 improved the fracture toughness, reduced friction coefficient, and wear rate of the coatings. 相似文献
2.
Plasma electrolytic oxidation (PEO) coatings in the aluminate-silicate-based mixture electrolyte solution with different duty cycles were successfully applied on Mg alloy. The corrosion behavior of the samples was evaluated by water contact angle test, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and immersion tests. Hydrophobic PEO coating could be obtained by adjusting the duty cycle of the applied electric signal. This coating considerably diminished the Mg dissolution and could enhance the impedance values of Mg alloy in 3.5 wt % NaCl solution. However, the surface of other PEO coated samples showed more hydrophilic properties compared to that of the uncoated sample. Dense structure of the modified PEO multiphase (including Mg2SiO4, MgO and MgAl2O4 phases) coating and also its appropriate thickness provided an effective barrier to remarkably delay corrosive solution penetration into the PEO coating. This phenomenon led to major decrease in anodic current density of alloy in chloride solution. 相似文献
3.
Junfeng Gou Jian Zhang Qiwen Zhang You Wang Chaohui Wang 《Journal of Thermal Spray Technology》2017,26(4):764-777
In this paper, the effect of nano-Si3N4 additives and plasma treatment on the wear behavior of Al2O3-8YSZ ceramic coatings was studied. Nano-Al2O3, nano-8YSZ (8 wt.% Y2O3-stabilized ZrO2) and nano-Si3N4 powders were used as raw materials to fabricate four types of sprayable feedstocks. Plasma treatment was used to improve the properties of the feedstocks. The surface morphologies of the ceramic coatings were observed. The mechanical properties of the ceramic coatings were measured. The dry sliding wear behavior of the Al2O3-8YSZ coatings with and without Si3N4 additives was studied. Nano-Si3N4 additives and plasma treatment can improve the morphologies of the coatings by prohibiting the initiation of micro-cracks and reducing the unmelted particles. The hardness and bonding strength of AZSP (Al2O3-18 wt.% 8YSZ-10 wt.% Si3N4-plasma treatment) coating increased by 79.2 and 44% compared to those of AZ (Al2O3-20 wt.% 8YSZ) coating. The porosity of AZSP coating decreased by 85.4% compared to that of AZ coating. The wear test results showed that the addition of nano-Si3N4 and plasma treatment could improve the wear resistance of Al2O3-8YSZ coatings. 相似文献
4.
Tabbetha A. Dobbins Richard Knight Merrilea J. Mayo 《Journal of Thermal Spray Technology》2003,12(2):214-225
High velocity oxy-fuel (HVOF) thermal spray has been successfully used to deposit yttria-stabilized zirconia (YSZ) for thermal
barrier coating (TBC) applications. Adherent coatings were obtained within a limited range of spray conditions using hydrogen
as fuel gas. Spray parameters such as hydrogen-to-oxygen ratio, spray distance, and substrate cooling were investigated. Spray
distance was found to have a pronounced effect on coating quality; adherent coatings were obtained for spray distances between
75 and 125 mm from the gun exit for the hydrogen-to-oxygen ratios explored. Compared to air plasma spray (APS) deposited YSZ
coatings, the HVOF deposited coatings were more fully stabilized in the tetragonal phase, and of similar density, surface
roughness, and cross-sectional microhardness. Notably, fracture surfaces of the HVOF coatings revealed a more homogeneous
structure. Many theoretical models predict that it should not be possible to melt YSZ in an HVOF flame, and therefore it should
not be possible to deposit viable YSZ coatings by this process. The experimental results in the present work clearly contradict
those expectations. The present results can be explained by taking into account the effect of partial melting and sintering
on particle cohesion, as follows. Combustion chamber pressures (P
o) of ∼3.9 bar (58.8 psi) realized during HVOF gun operation allows adiabatic flame temperature values that are above the zirconia
melting temperature. Under these conditions, the Ranz-Marshall heat transfer model predicts HVOF sprayed particle surface
temperatures T
p that are high enough for partial melting of small (∼10 μm) zirconia particles, T
p=(1.10−0.95)T
m. Further analysis shows that for larger particles (38 μm), adherent coatings are produced when the particle temperature,
T
p=0.59−0.60 T
m, suggesting that sintering may have a role in zirconia particle deposition during HVOF spray. These results suggest two different
bonding mechanisms for powders having a broad particle size distribution. 相似文献
5.
P. Karuna Purnapu Rupa Prashant Sharma R. M. Mohanty K. Balasubramanian 《Journal of Thermal Spray Technology》2010,19(4):816-823
The effect of addition of 5 to 30 wt.% boron carbide (B4C) on structure and hardness of plasma sprayed zirconia (ZrO2) coating has been studied in this paper. The coatings have exhibited a uniform porous microstructure. A reaction between
B4C and ZrO2 resulted in the formation of a diboride (ZrB2) phase. The presence of ZrB2 in the coatings has been confirmed through x-ray diffraction studies. In order to study the effect of critical processing
parameters, the coatings have also been deposited under increased hydrogen flow rate (11.8 SLM). This increased the abrasion
integrity of the coatings. A high yield of ZrB2 was observed in the case of 15 wt.% B4C addition. Hardness of the coatings have been influenced by the porosities, additionally generated by the formation of ZrB2. Under increased hydrogen flow rate, a composite coating of ZrO2-ZrB2 was obtained from the ZrO2-B4C powder mixture. 相似文献
6.
In previous studies, it has been demonstrated that nanostructured Al2O3-13 wt.%TiO2 coatings deposited via air plasma spray (APS) exhibit higher wear resistance when compared to that of conventional coatings.
This study aimed to verify if high-velocity oxy-fuel (HVOF)-sprayed Al2O3-13 wt.%TiO2 coatings produced using hybrid (nano + submicron) powders could improve even further the already recognized good wear properties
of the APS nanostructured coatings. According to the abrasion test results (ASTM G 64), there was an improvement in wear performance
by a factor of 8 for the HVOF-sprayed hybrid coating as compared to the best performing APS conventional coating. When comparing
both hybrid and conventional HVOF-sprayed coatings, there was an improvement in wear performance by a factor of 4 when using
the hybrid material. The results show a significant antiwear improvement provided by the hybrid material. Scanning electron
microscopy (SEM) at low/high magnifications showed the distinctive microstructure of the HVOF-sprayed hybrid coating, which
helps to explain its excellent wear performance.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
7.
Y(NO3)3 and NH3·H2O were used as a raw materials,and nano-Y2O3 powder was successfully synthesized by a precipitation method.Employing TEOS as a raw material,SiO2 powder was successfully prepared by a alkoxide-hydrolysis method,and a Y2O3/SiO2 composite powder was obtained by coating.The Y2O3,SiO2,and Y2O3/SiO2 powders were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),and Fourier transform infrared spectrophotometer(FT-IR);the Y2O3 and Y2O3/SiO2 powders were further examined ... 相似文献
8.
Dianran Yan Yanchun Dong Yong Yang Lei Wang Xueguang Chen Jining He Jianxin Zhang 《Journal of Thermal Spray Technology》2011,20(6):1269-1277
The microstructure of the coating prepared by reactive plasma spraying Fe2O3/Al composite powders was characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy.
The results indicated that the coating exhibited nanostructured microstructure which consisted of FeAl2O4, Fe or Fe solid solution, Al2O3 and a little FeAl. In the composite coating, spherical Fe particles (tens of nanometers to hundreds of nanometers) were distributed
uniformly within the equiaxed and columnar nanograins FeAl2O4 matrix. There were two kinds of Al2O3 phases present in the composite coating. One kind was nano-sized Al2O3 particles uniformly dispersed within the matrix, forming eutectic structure of (FeAl2O4 + γ-Al2O3); the other was 1-1.5 μm Al2O3 particles embedded individually within the matrix. The composite coating had higher toughness than the conventional microstructured
Al2O3 coating. 相似文献
9.
Nanostructured and conventional Al2O3-13wt.%TiO2 ceramic coatings were prepared by plasma spraying with nanostructured agglomerated and conventional powders, respectively.
The microstructure and microhardness of the coatings were investigated using scanning electron microscopy (SEM), energy dispersive
spectroscopy (EDS), and microhardness measurement. Meanwhile, the friction and wear behaviors were analyzed and compared using
a ball-on-disk tribometer. The results show that the conventional coating has lamellar stacking characteristic and has some
pores. However, the nanostructured coating shows a bimodal microstructure, which is composed of both fully melted regions
and partially melted regions. According to the microstructural difference, the partially melted regions can be divided into
liquid-phase sintered regions (a three-dimensional net or skeleton-like structure: Al2O3-rich submicron particles embedded in the TiO2-rich matrix) and solid-phase sintered regions (remained nanoparticles). The microstructural characteristics of the liquid-phase
sintered region are formed due to the selective melting of TiO2 nanoparticles during plasma spraying. On the other hand, the TiO2 and Al2O3 nanoparticles of the solid-phase sintered regions are all unmelted during plasma spraying. Due to the existence of nanostructured
microstructures, the nanostructured coating has a higher microhardness, a lower friction coefficient, and a better wear resistance
than the conventional coating. 相似文献
10.
Shi Hong Zhang Ming Xi Li Tong Yul Cho Jae Hong Yoon Wei Fang Yun Kon Joo Jin Ho Kang Chan Gyu Lee 《Metals and Materials International》2008,14(3):315-319
The effects on the microstructures and phases of coating layers by the addition of micron-sized (m) and nano-sized (n) (m&n)
Sm2O3 powders were investigated. The coating materials, which were prepared by means of 2.0 kW CO2 laser cladding, consist of a powder mixture of m Ni-based alloy (NBA) powders comprising 1.5 wt.% m Sm2O3 and 3.0% n Sm2O3 powders. The results indicate that γ-Ni, Cr23C6 and Ni3B are the primary phases of the NBA coatings. The Fe7Sm and Ni3Si phases are highlighted by the addition of m&n Sm2O3 powders. From the substrate, planar crystal layers are first grown in all NBA and m&n Sm2O3/NBA coatings. The dendrite growth then occurs as a result of the addition of the m Sm2O3 powder, and the equiaxed dendrite growth occurs as a result of the addition of the n Sm2O3. With the addition of a rare earth oxide such as Sm2O3 powder, the width of the planar crystal becomes smaller than that of the NBA coating. 相似文献
11.
An isothermal section of the system Al2O3-CaO-CoO at 1500 K has been established by equilibrating 22 samples of different compositions at high temperature and phase
identification by optical and scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy after quenching
to room temperature. Only one quaternary oxide, Ca3CoAl4O10, was identified inside the ternary triangle. Based on the phase relations, a solid-state electrochemical cell was designed
to measure the Gibbs energy of formation of Ca3CoAl4O10 in the temperature range from 1150 to 1500 K. Calcia-stabilized zirconia was used as the solid electrolyte and a mixture
of Co + CoO as the reference electrode. The cell can be represented as: From the emf of the cell, the standard Gibbs energy change for the Ca3CoAl4O10 formation reaction, CoO + 3/5CaAl2O4 + 1/5Ca12Al14O33 → Ca3CoAl4O10, is obtained as a function of temperature: /J mol−1 (±50) = −2673 + 0.289 (T/K). The standard Gibbs energy of formation of Ca3CoAl4O10 from its component binary oxides, Al2O3, CaO, and CoO is derived as a function of temperature. The standard entropy and enthalpy of formation of Ca3CoAl4O10 at 298.15 K are evaluated. Chemical potential diagrams for the system Al2O3-CaO-CoO at 1500 K are presented based on the results of this study and auxiliary information from the literature. 相似文献
12.
Mojtaba Vakili-Azghandi Arash Fattah-alhosseini Mohsen K. Keshavarz 《Journal of Materials Engineering and Performance》2016,25(12):5302-5313
Corrosion resistance improvement of plasma electrolyte oxidation coatings on 6061 aluminum alloy in silicate electrolyte containing Al2O3 nano-particles was studied, with particular emphasis on the microstructure, coating growth, and corrosion behavior in 3.5 wt.% NaCl solution. The microstructure of coatings, their thickness, and phase composition were characterized using scanning electron microscopy and x-ray diffraction. All characterization data showed that the maximum coating thickness and lowest amount of porosity were obtained in a low concentration of KOH, a high concentration of Na2SiO3, and moderate concentration of Al2O3 nano-particles in the electrolyte. This combination describes the optimum plasma electrolytic oxidation electrolyte, which has the best conductivity and oxidizing state, as well as the highest incorporation of electrolyte components in the coating growth process. On the other hand, incorporation and co-deposition of Al2O3 nano-particles were more pronounced than SiO3 2? ions in some level of molar concentration, which is due to the higher impact of electron discharge force on the adsorption of Al2O3 nano-particles. The electrochemical results showed that the best protective behavior was obtained in the sample having a coat with the lowest porosity and highest thickness. 相似文献
13.
Yaran Niu Zhong Wang Jun Zhao Xuebin Zheng Yi Zeng Chuanxian Ding 《Journal of Thermal Spray Technology》2017,26(1-2):100-107
In this work, ZrB2-20 vol.% MoSi2 (denoted as ZM) composite coatings were fabricated by atmospheric plasma spray (APS) and vacuum plasma spray (VPS) techniques, respectively. Phase composition and microstructure of the composite coatings were characterized. Their oxidation behaviors and microstructure changes at 1500 °C were comparatively investigated. The results showed that VPS-ZM coating was composed of hexagonal ZrB2, tetragonal and hexagonal MoSi2, while certain amount of ZrO2 existed in APS-ZM coating. The oxide content, surface roughness and porosity of VPS-ZM coating were apparently lower than those of APS-ZM coating. The mass gain of APS-ZM coating was maximum at the beginning (1500 °C, 0 h) and then decreased with the oxidation time extending, while the mass of VPS-ZM coating gradually increased with increasing the oxidation time. The possible reasons for the different oxidation behaviors of the two kinds of coatings were analyzed. 相似文献
14.
S. Sadreddini S. Rahemi Ardakani H. Rassaee 《Journal of Materials Engineering and Performance》2017,26(5):2032-2039
In the present work, nano-composites of Ni-P-SiO2-Al2O3 were coated on AZ91HP magnesium alloy. The surface morphology of the nano-composite coating was studied by field emission scanning electron microscopy (FESEM). The amount of SiO2 in the coating was determined by energy-dispersive analysis of x-ray (EDX), and the crystalline structure of the coating was examined by x-ray diffractometer (XRD). All the experiments concerning the corrosion behavior of the coating carried out in 3.5 wt.% NaCl solution and evaluated by electrochemical impedance spectroscopy (EIS) and polarization technique. The results showed that an incorporation of SiO2 and Al2O3 in Ni-P coating at the SiO2 concentration of 10 g/Land 14 g/LAl2O3 led to the lowest corrosion rate (i corr = 1.3 µA/cm2), the most positive E corr and maximum microhardness (496 VH). Furthermore, Ni-P-SiO2-Al2O3 nano-composite coating possesses less porosity than that in Ni-P coating, resulting in improving corrosion resistance. 相似文献
15.
Air plasma-sprayed conventional alumina-titania (Al2O3-13wt.%TiO2) coatings have been used for many years in the thermal spray industry for antiwear applications, mainly in the paper, printing,
and textile industries. This work proposes an alternative to the traditional air plasma spraying of conventional aluminatitania
by high-velocity oxyfuel (HVOF) spraying of nanostructured titania (TiO2). The microstructure, porosity, hardness (HV 300 g), crack propagation resistance, abrasion behavior (ASTM G65), and wear
scar characteristics of these two types of coatings were analyzed and compared. The HVOF-sprayed nanostructured titania coating
is nearly pore-free and exhibits higher wear resistance when compared with the air plasma-sprayed conventional alumina-titania
coating. The nanozones in the nanostructured coating act as crack arresters, enhancing its toughness. By comparing the wear
scar of both coatings (via SEM, stereoscope microscopy, and roughness measurements), it is observed that the wear scar of
the HVOF-sprayed nanostructured titania is very smooth, indicating plastic deformation characteristics, whereas the wear scar
of the air plasma-sprayed alumina-titania coating is very rough and fractured. This is considered to be an indication of a
superior machinability of the nanostructured coating. 相似文献
16.
Ying Lin Baozhi Zeng Yingbin Lin Xiaowei Li Guiying Zhao Ting Zhou Heng Lai Zhigao Huang 《稀有金属(英文版)》2012,31(2):145-149
Olivine structured LiFePO4/C (lithium iron phosphate) and Mn2+-doped LiFe0. 98Mn0. 024/C powders were synthesized by the solid-state reaction. The effects of manganese partial substitution and different carbon content coating on the surface of LiFePO4 were considered. The structures and electrochemical properties of the samples were measured by X-ray diffraction (XRD), cyclic voltammetry (CV), charge/discharge tests at different current densities, and electrochemical impedance spectroscopy (EIS). The electrochemical properties of LiFePO4 cathodes with x wt. % carbon coating (x=3, 7, 11, 15) at γ=0. 2C, 2C (1C=170 mAh·g-1) between 2. 5 and 4. 3 V were investigated. The measured results mean that the LiFePO4 with 7 wt. % carbon coating shows the best rate performance. The discharge capacity of LiFe0. 98Mn0. 02PO4/C composite is found to be 165 mAh·g 1 at a discharge rate, γ=0. 2C, and 105 mAh·g-1 at γ=2C, respectively. After 10cycles, the discharge capacity has rarely fallen, while that of the pristine LiFePO4/C cathode is 150 mAh·g-1 and 98 mAh·g-1 at γ=0. 2 and 2C, respectively. Compared to the discharge capacities of both electrodes above, the evident improvement of the electrochemical performance is observed, which is ascribed to the enhancement of the electronic conductivity and diffusion kinetics by carbon coating and Mn2+-substitution. 相似文献
17.
Yuxia Cao 《Journal of Thermal Spray Technology》2016,25(4):650-659
NiCr/Cr3C2-hBN composite coatings with different contents of hBN were prepared by atmospheric plasma-spray technology. The microstructural, mechanical, and tribological properties of the coatings were systematically investigated. The results show that the flowability and apparent density of NiCr/Cr3C2-hBN composite powders, as well as the microhardness and tensile strength of the NiCr/Cr3C2-hBN composite coating, gradually decrease with the increase of hBN in the composite powders. The addition of hBN is benefit to the friction coefficient of the coatings, but it is positive to the wear rate. When the content of hBN is up to 20%, the friction coefficient of the composite coating is lowest, but the wear rate of the composite coating is highest. 相似文献
18.
Yinyin Zhang Sylvie Descartes Phuong Vo Richard R. Chromik 《Journal of Thermal Spray Technology》2016,25(3):473-482
Cu and Cu-MoS2 coatings were fabricated by cold spray, and the fretting wear performance of the two coatings was compared. A mixture (95 wt.% Cu + 5 wt.% MoS2) was used as feedstock for the composite coating. Coatings were sprayed with identical gas flow conditions on the substrates pre-heated to approximately 170 °C. The morphology of coating top surface and polished cross sections was analyzed by scanning electron microscopy (SEM) and light optical microscopy (LOM). The influence of MoS2 on Cu deposition was examined. The local MoS2 concentration within the coating was found to affect the hardness. Fretting tests were carried out at two different normal loads, and the influence of MoS2 on friction and wear was studied. The morphology and elemental compositions of the wear scars and wear debris were observed by SEM and energy dispersive x-ray spectroscopy (EDS), respectively. 相似文献
19.
Archana Loganathan Sara Rengifo Alexander Franco Hernandez Yusuf Emirov Cheng Zhang Benjamin Boesl Jeganathan Karthikeyan Arvind Agarwal 《Journal of Thermal Spray Technology》2017,26(7):1585-1597
Tungsten disulfide (WS2) has excellent solid lubrication properties due to its 2D layered structure. This study focuses on depositing Al-2 wt.% WS2 composite coating by cold spray technique. The effect of WS2 addition on the microstructure, mechanical and tribological properties of the composite coatings is examined in the as-deposited and heat-treated conditions. After heat treatment, the coating density increased to 99% with improved intersplat bonding. The microhardness of the heat-treated Al-2 wt.% WS2 coating increased by 56% as compared to the as-sprayed coating. The wear resistance of heat-treated Al-2 wt.% WS2 coating improved by 75% with a synergistic reduction in the coefficient of friction (COF) by 51%. Transmission electron microscopy investigation reveals the presence of layered WS2 within aluminum splats with a strong interface. This study shows that cold spraying can be effectively used to integrate 2D layered WS2 as a solid lubricant in the metallic coatings. 相似文献
20.
Xin Zhong Yaran Niu Liping Huang Hong Li Xuebin Zheng Chuanxian Ding Jinliang Sun 《Journal of Thermal Spray Technology》2017,26(1-2):203-210
In the present work, Yb2Si2O7 powder was synthesized by solid-state reaction using Yb2O3 and SiO2 powders as starting materials. Atmospheric plasma spray technique was applied to fabricate Yb2Si2O7 coating. The phase composition and microstructure of the coating were characterized. The density, open porosity and Vickers hardness of the coating were investigated. Its thermal stability was evaluated by thermogravimetry and differential thermal analysis (TG-DTA). The thermal diffusivity and thermal conductivity of the coating were measured. The results showed that the as-sprayed coating was mainly composed of crystalline Yb2Si2O7 with amorphous phase. The coating had a dense structure containing defects, such as pores, interfaces and microcracks. The TG-DTA results showed that there was almost no mass change from room temperature to 1200 °C, while a sharp exothermic peak appeared at around 1038 °C in DTA curve, which indicated that the amorphous phase crystallized. The thermal conductivity of the coating decreased with rise in temperature up to 600 °C and then followed by an increase at higher temperatures. The minimum value of the thermal conductivity of the Yb2Si2O7 coating was about 0.68 W/(m K). 相似文献