Al2O3含量对Ni-W-Al2O3复合镀层性能的影响

采用直流电沉积技术在45#钢基体上制备Ni-W-Al2O3复合镀层,通过显微硬度计、摩擦磨损试验机、划痕仪等研究Al2O3颗粒含量对复合镀层的力学性能及摩擦磨损性能等的影响,并用SEM、XRD对复合镀层的表面断面形貌、物相结构进行分析.结果表明,Ni-W-Al2O3复合镀层为晶态结构,其耐磨性能明显优于Ni-W镀层,且随着Al2O3颗粒含量的增加,复合镀层的摩擦系数呈现出先减小后增大趋势.磨损形式主要表现为粘着磨损与磨粒磨损.复合镀层与基体之间结合牢固,结合力大小约为70~80 N.当Al2O3含量为5 g/L时,复合镀层的综合性能最优.     

Mo_5Si_3-Al_2O_3复合材料的制备及抗氧化性能研究

采用机械化学还原法结合热压烧结制备了Mo_5Si_3-Al_2O_3复合材料,并对复合材料在600℃下的氧化行为进行了研究。结果表明:以MoO_3粉、Mo粉、Si粉和Al粉为原料,机械球磨10h,可获得具有纳米晶结构的Mo_5Si_3-Al_2O_3复合粉体;相比纯Mo5Si3试样,Mo_5Si_3-Al_2O_3复合材料的烧结相对密度和硬度提高,分别达97.2%和1350HV;Al_2O_3的引入可有效防止Mo_5Si_3的低温"粉化"现象,使Mo_5Si_3-Al_2O_3复合材料的抗氧化性明显提高,其氧化动力学曲线呈近似抛物线规律。     

大气等离子喷涂制备Al_2O_3阻氚渗透涂层研究

在金属结构件上制备陶瓷阻氚渗透涂层是先进核反应堆的关键技术之一。本文采用大气等离子喷涂的方法在316L不锈钢上制备了Al2O3/NiCrAlY涂层,通过XRD、FESEM研究了Al2O3喷涂粉末和涂层特性,并对涂层的结合强度、阻氢渗透性能进行研究。实验结果表明:以α-Al2O3为主相的造粒粉末喷涂后,涂层沉积过程中产生部分γ-Al2O3;涂层体系各层界面结合良好,Al2O3层和NiCrAlY层之间的平均结合强度达到34.7MPa;600℃时Al2O3涂层的阻氢渗透因子为5065,氢渗透率降低3个数量级,Al2O3涂层具有良好的阻氢氚渗透效果。     

等离子喷涂Al2O3涂层CO2连续激光反射性能的研究

采用等离子喷涂法制备了Al2O3涂层,研究了相结构对CO2连续激光反射率的影响。结果表明,Al2O3涂层中的主相为γ-Al2O3,涂层对CO2连续激光的反射率为23.65%±0.80%。γ-Al2O3的激光反射率高于α-Al2O3,主要原因是α-Al2O3和γ-Al2O3的晶体结构不同,在与激光相互作用时,由于γ-Al2O3存在电子轨道交叠,电子带间跃迁能力较强,提高了其对CO2连续激光的反射率。等离子喷涂Al2O3涂层在激光辐照过程中存在γ-Al2O3到α-Al2O3的相变,使得涂层的反射率下降。     

Recycling of High Ferrous Bauxite Reducing Slag for Synthesis of CaAl2 Si2 O8-Al2 O3-CaAl12 O19 Composite

CaAl_2 Si_2 O_8-Al_2O_3-CaAl_(12) O_(19)( CAS_2-Al_2O_3-CA_6) composite was synthesized through reaction sintering alumina and bauxite reducing slag.The CAS_2-Al_2O_3-CA_6 composite was mainly composed of α-Al_2O_3,CAS_2,and CA_6.Gehlenite( Ca_2Al_2 SiO_7,C_2AS) phase was effectively transformed to CAS_2 and CA_6through high-temperature reaction sintering under weak oxidizing atmosphere at 1400 ℃ for 4h.SEM( scanning electron microscopy) and EDS( energy dispersive spectroscopy) analysis indicated that black and needle-shaped Al_2O_3,rhombic or irregular polygonal-shaped Fe Al_2O_4,and glassy phase Ca_2Al_2 SiO_7disappeared after the reaction sintering.The light gray and flaky hexagon crystals of Ca Al_(12)O_(19)(10μm) and the grainy particles of Al_2O_3( 2-7μm) were observed in the CAS_2-Al_2O_3-CA_6 composite.The gray crystals of CAS_2 act as the binding phase and are distributed around CA_6 and Al_2O_3.CAS_2-Al_2O_3-CA_6 composite exhibits high refractoriness and service temperature,which are 1650 ℃ and 1450 ℃,respectively.Reaction sintering of alumina and bauxite reducing slag is a feasible method for the synthesis of CAS_2-Al_2O_3-CA_6 composite.     

Preparation and tribological performance of electrodeposited Ni-TiB2-Dy2O3 composite coatings

TiB2 and Dy2O3 were used as codeposited particles in the preparation of Ni-TiB2-Dy2O3 composite coatings to improve its per-formance. Ni-TiB2-Dy2O3 composite coatings were prepared by electrodeposition method with a nickel cetyltrimethylanunonium bromide and hexadecylpyridinium bromide solution containing TiB2 and Dy2O3 particles. The content of codeposited TiB2 and Dy2O3 in the compos-ite coatings was controlled by adding TiB2 and Dy2O3 particles of different concentrations into the solution, respectively. The effects of TiB2 and Dy2O3 content on microhardness, wear mass loss and friction coefficients of composite coatings were investigated. The composite coat-ings were characterized by X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES) and scanning electron microscopy (SEM) techniques. Ni-TiB2-Dy2O3 composite coatings showed higher microhardness, lower wear mass loss and friction coefficient compared with those of the pure Ni coating and Ni-TiB2 composite coatings. The wear mass loss of Ni-TiB2-Dy2O3 composite coatings was 9 and 1.57 times lower than that of the pure Ni coating and Ni-TiB2 composite coatings, respectively. The friction coefficient of pure Ni coating, Ni-TiB2 and Ni-TiB2-Dy2O3 composite coatings were 0.723, 0.815 and 0.619, respectively. Ni-TiB2-Dy2O3 composite coat-ings displayed the least friction coefficient among the three coatings. DY2O3 particles in composite coatings might serve as a solid lubricant between contact surfaces to decrease the friction coefficient and abate the wear of the composite coatings. The loading-bearing capacity and the wear-reducing effect of the Dy2O3 particles were closely related to the content of Dy2O3 particles in the composite coatings.     

Effect of Al2O3 on Structure and Wearability of Composite Coating

Asasurface strengtheningtechnology ,thether malsprayhasevolvedfromearlynormal protectivecoatingtocurrentfunctionalcoating .Thedevelopmentofcompositepowderisanimportantbreakthroughinthisfield .Particularly ,thenewlydevelopedmetal basedceramiccoatings ,such…     

Y2O3对NiCr-Cr3C2金属陶瓷涂层热腐蚀性能影响行为研究

本文利用超音速火焰喷涂技术(HVOF),在20G钢表面制备了掺杂1wt.%、3wt.%、5wt.%三种不同含量Y2O3的NiCr-Cr3C2金属陶瓷复合涂层,并探究了其在650℃,Na2SO4/K2SO4熔盐环境中的热腐蚀性能。利用扫描电镜(SEM)、显微硬度计、拉伸试验机等对涂层的微观结构和力学性能进行了表征,利用X射线衍射仪(XRD)、拉曼光谱、X射线能谱仪(EDS)对复合涂层热腐蚀产物形貌、物相进行分析。结果表明掺杂1wt.%Y2O3的NiCr-Cr3C2复合涂层结构致密、孔隙率低、结合强度高,显微硬度达到801HV。热腐蚀过程中掺杂Y2O3的NiCr-Cr3C2复合涂层表面均生成耐蚀性良好且致密的Cr2O3膜。随着Y2O3掺杂量的增加,涂层的耐热腐蚀性能先升高后下降,当Y2O3掺杂量为1wt.%时,复合涂层表现出最佳的耐热腐蚀性能。     

料浆涂覆法制备W-Si-ZrO_2-Y_2O_3高温抗氧化涂层的组织与高温氧化行为

采用料浆涂覆和多步反应烧结工艺在难熔钨合金表面制备W-Si-ZrO_2-Y2O3高温抗氧化陶瓷复合涂层,对涂层的成分、组织特征及1 700℃下的抗氧化性能进行分析。结果表明,在反应烧结过程中涂层形成了以WSi2为主体,ZrO_2和Y2O3均匀分布的多相陶瓷复合结构,涂层与基体形成良好的冶金结合。涂层在1 700℃空气环境中具有良好的抗氧化性能,高温下其表面生成光滑致密的Si O2玻璃膜,有效抗氧化寿命达14 h。     

等离子喷涂制备铁基复合陶瓷涂层的研究

以铝粉和氧化铁粉作原料,采用等离子反应合成技术制备出了金属颗粒增韧的FeAl2O4-Al2O3-Fe复合陶瓷涂层。研究分析了复合涂层的组织及其性能。结果表明：等离子反应合成得到了以层状基体相FeAl2O4与硬质相Al2O3为骨架,球状Fe相弥散分布于基体相上的复合涂层。复合涂层的断裂韧性和结合强度明显优于普通Al2O3涂层,特别是复合涂层的具有较高的耐磨性能。     

低压等离子喷涂CoCrAlYTa-10%Al2O3涂层组织及性能研究

在SUS304钢基体上利用低压等离子喷涂（LPPS）技术制备CoCrAlYTa-10%Al2O3涂层,并通过扫描电子显微镜（SEM）、X射线衍射仪、显微硬度计对涂层的组织与性能进行了分析,研究了涂层的耐冲刷腐蚀以及抗高温氧化性能。结果表明：LPPS制备的CoCrAlYTa-10%Al2O3涂层结构致密,硬度高,涂层与基体结合良好,具有良好的抗冲刷腐蚀及抗高温氧化性能。     

等离子喷涂Al_2O_3-TiO_2陶瓷涂层的显微组织及摩擦学性能

以Al_2O_3-TiO_2(x=0%,3%,13%,20%,40%,质量分数)复合陶瓷粉末为原料,采用等离子喷涂工艺在316L不锈钢基体表面制备5种陶瓷涂层。利用扫描电镜(SEM)、能谱仪(EDS)和X线衍射仪(XRD)、荧光金相显微镜分析粉末和涂层形貌、微观结构、物相组成及涂层孔隙率;利用显微硬度计及摩擦磨损试验机测试涂层力学及摩擦学性能,观察试样磨损形貌,分析磨损机理。结果表明:涂层呈典型的等离子喷涂层状堆积特征,涂层与基体结合良好。随TiO_2含量增加,涂层主相由γ-Al_2O_3向Al_2TiO_5相过渡,涂层韧性升高,硬度和孔隙率降低。在大气环境下,低TiO_2含量的涂层(Al_2O_3、AT3)发生应力疲劳磨损,高TiO_2含量的涂层(AT13、AT20和AT40)发生应变疲劳磨损;而在水环境下,5种涂层均发生应力疲劳磨损。     

CeO2对不锈钢基SiO2-BaO-Al2O3-Cr2O3陶瓷涂层性能的影响

采用高温熔烧法于1Cr18Ni9Ti不锈钢基材表面制备掺CeO2的SiO2-BaO-Al2O3-Cr2O3陶瓷涂层,研究了不同含量CeO2对涂层的抗氧化性、抗热震性和硬度的影响。研究结果表明,含CeO2的不锈钢基SiO2-BaO-Al2O3-Cr2O3陶瓷涂层能有效阻止不锈钢基体的氧化增重,提高涂层的抗热震性能及硬度。本实验条件下,CeO2含量2.8%时,涂层具有最好的抗氧化性能和抗热震性能。     

Research on Glass Forming Ability of Er2O3 -Al2O3 -B2O3 -SiO2 System

The glass forming range of Er2O3-Al2O3-B2O3-SiO2 system was explored, and the effect of the content of Al2 O3 and Er2 O3 on glass-forming region was experimentally examined. It is shown that the region of glass formation range expends when the content of Al2O3 is changed from 15% to 20%, while it shrinks when the content of Er2O3 is changed from 20% to 30%. At the same time, the glass forming ability of Er2O3-Al2O3-B2O3-SiO2 system was also discussed using a value of β, which is an indication of crystallization tendency of glasses, calculated from thermo-analysis data. It is found that the glass forming ability of Er2O3-Al2O3-B2O3- SiO2 glasses is poor, while the glasses network may be enhanced when Al2O3 is added to the system, the glass forming ability being heightened. In addition, the crystallization temperatures of the rare earth glasses were determined using differential thermal analysis technique. The Er2O3-Al2O;-B2O3-SiO2 glass samples were heat treated at 1000,1100 and 1260℃ respectively. The results show that it is the Er2O3 phase that separates out from the glasses after crystaline heat treatment, and it is tiered up in glasses, as detected through XRD and SEM. This indicates that the phase separation occurs when the glasses are heated, Er3 being mainly distributed in the boron rich phase, then separated out from glasses, while the silicate rich phase remaining glassy state.     

Structure and Mechanical Properties of Ni-P-Nano Al2O3 Composite Coatings Synthesized by Electroless Plating

Ni-P-nano Al2O3 composite coatings were deposited by electroless plating,and their microstructures were observed by SEM（scanning electron microscope）.The microhardness and the wear resistance of the Ni-P-nano Al2O3 composite coatings were measured using microhardness tester and block-on-ring tribometer,respectively,and the comparison with those of Ni-P coatings or Ni-P-micro Al2O3 coating was given.The influences of aging temperature on their hardness and wear resistance were analyzed.The results showed that the nano Al2O3 particles were distributed uniformly in the Ni-P-Al2O3 coatings.Among three kinds of Ni-P based coatings,the hardness and wear resistance of Ni-P-nano Al2O3 coatings were largest,and the maximum values could be obtained at 400 ℃.This indicated that the precipitation of nano Al2O3 particles would improve the hardness and wear resistance of the Ni-P coatings.     

Oxidation Resistance of Fe-13Cr Alloy with Micro-Laminated （ZrO2-Y2O3 ） / （Al2O3-Y2O3 ） Films

Oxidationofmetalsoralloysathightemperatures canbetreatedasaspecialcaseofmetalliccorrosion,inwhichsolidphasesinteracteitherwithaliquid agentoragaseousagent.Toimprovetheresistance againsthigh temperatureoxidationandelectrochemical corrosionofmetals,thesurfa…     

铁基Cr3C2复合涂层的组织及性能研究

利用空气燃料超音速火焰喷涂技术(HVAF)在D2钢表面制得Cr3C2-FeCrBSi复合涂层.借用光学显微镜(OM)、维氏硬度计、扫描电镜(SEM)、拉伸试验机及摩擦磨损试验机对复合涂层的显微结构、力学性能及摩擦磨损性能进行表征与测试,研究了不同比例纳米-微米Cr3C2陶瓷增强相对复合涂层组织结构及性能的影响.试验结果...     

Catalytic Incineration of Acrylonitrile with Platinum Supported on Al2O3

The catalytic decomposition of acrylonitrile with catalysts was investigated in a bench scale fixed bed reactor in this study. Two catalysts, including Pt/γ-Al2O3 and Cr2O3/α-Al2O3, were tested to study their catalytic activity in the complete oxidation of acrylonitrile. The results show that the Pt/γ-Al2O3 catalyst has better performance. The operating parameters such as operating temperature, acrylonitrile concentration, space velocity, and oxygen concentration were conducted in a series of experiments on the Pt/γ-Al2O3 catalyst. The results indicate that decomposition efficiency increases with temperature and oxygen concentration and decreases with the increases of space velocity and acrylonitrile concentration. With a regression model, the operating temperature is the most effective parameter on the decomposition of acrylonitrile. Carbon dioxide is the dominant product and carbon monoxide is an insignificant product of the decomposition of acrylonitrile. Material balance on carbon is good for the experiments. According to the BET and elemental analyzer analysis, major factors that cause the deactivation effect may result from nitrogen poisoning and carbon masking on the catalyst surface, especially at lower temperatures.     

Preparation and performance of electrodeposited Ni-TiB₂-Sm₂O₃ composite coatings

Sm2O3 and TiB2 were used as codeposited particles in electrodeposition Ni-TiB2-Sm2O3 composite coatings to improve its performance. Ni-TiB2-Sm2O3 composite coatings were electrodeposited in the nickel sulfate,hexadecylpyridinium bromide and cetyltrimethylammonium bromide solution containing TiB2 and Sm2O3 particles. The content of codeposited Sm2O3 in the composite coating was controlled by changing the concentrations of Sm2O3 particles in the solution. The composite coatings were characterized with X-ray diffraction(XRD) and inductively coupled plasma-atomic emission spectrometer(ICP-AES) . The effects of Sm2O3 content on microhardness,wear weight loss and friction coefficient of composite coatings were investigated,respectively. The microhardness of the Ni-TiB2-Sm2O3 composite coatings was 19.35%,16.58%,2.03% higher than that of the Ni coating,Ni-Sm2O3 and Ni-TiB2 composite coatings,respectively. The wear weight loss of the Ni-TiB2-Sm2O3 composite coatings was 7,2.33,1.22 times lower than that of the Ni coating,Ni-Sm2O3 and Ni-TiB2 composite coatings,respectively. The friction coefficient of the Ni coating,Ni-Sm2O3,Ni-TiB2 and Ni-TiB2-Sm2O3 composite coatings were 0.712,0.649,0.850 and 0.788,respectively. The loading-bearing capacity and the wear-reducing effect of the Sm2O3 particles were closely related to the content of Sm2O3 particles in the composite coatings.     

Microstructure and high-temperature properties of Fe-Ti-Cr-Mo-B-C-Y_2O_3 laser cladding coating

Fe-based composite coatings were fabricated on 5 CrNiMo die steel by laser beam melting a precursor mixture of ferrotitanium,ferrochromium,ferromolybdenum,B4 C and Y_2 O_3 powders.Micro structure and properties of the coatings were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),energy-dispersive spectrometer(EDS),resistance furnace and high-temperature tribometer.The results show that(Ti,Mo)C particles with flower-like and(Ti,Mo)B_2 with block-like shapes are in situ formed during laser cladding.Volume faction of multiple ceramic particles increases with the increasing of Y_2 O_3.The cumulative oxidation mass of the coating with 2 wt% Y_2 O_3 is decreased by one-third than that of the coating without Y_2 O_3.The oxidation layer of the coating with Y_2 O_3 is getting smooth.Meanwhile,high temperature wear volume loss of the coating with 2 wt% Y_2 O_3 is about 40% that of the coating without Y_2 O_3.The coating with 2 wt% Y_2 O_3 shows a smoother wear scar and few flat grooves are observed after high temperature wear test.