SiC-MoSi_2/ZrO_2-MoSi_2 coating to protect C/C composites against oxidation

To improve the oxidation resistance of carbon/carbon （C/C） composites in air at high temperatures, a SiC- MoSi2/ZrO2-MoSi2 coating was prepared on the surface of C/C composites by pack cementation and slurry method. The microstructures and phase compositions of the coated C/C composites were analyzed by scanning electron microscopy and X-ray diffraction, respectively. The result shows that the SiC-MoSi2/ZrO2-MoSi2 coating is dense and crack-free with a thickness of 250-300 μm. The preparation and the high temperature oxidation property of the coated composites were investigated. The as-received coating has excellent oxidation protection ability and can protect C/C composites from oxidation for 260 h at 1773 K in air. The excellent anti-oxidation performance of the coating is considered to come from the formation of ZrSiO4, which improves the stability of the coating at high temperatures.

Characteristics of electrodeposited RE-Ni-W-B-B_4C-MoS_2 composite coating

The high temperature oxidation resistance of RE Ni W B B 4C MoS 2 composite coating, the effects of electrodeposition conditions on the morphologies of the coating and the effect of heat treatment temperature on its hardness, abrasion resistance and phase structure were investigated by using scanning electron microscope(SEM), X ray diffractometer, microhardness tester and abrasion machine. The results show that the oxidation degree of RE Ni W B B 4C MoS 2 composite coating is small when the temperature is lower than 700 ℃, but it increases sharply when the temperature is higher than 700 ℃. The hardness of RE Ni W B B 4C MoS 2 composite coating increases with increasing heat treatment temperature, it comes up to the maximum value at 400 ℃,but it decreases gradually if the temperature rises continuously. The most favourable abrasion resistance was attained after RE Ni W B B 4C MoS 2 composite coating being heat treated at 400 ℃. Without heat treating, it is mainly amorphous and partially crystallized, but wholly crystallized after being heat treated at 500 ℃. RE in the composite coating is in the form of CeO 2 and additions of CeO 2 and B 4C can enhance the thermostability of RE Ni W B B 4C MoS 2 composite coating.

SLM铝合金表面喷射电沉积Ni-MoS_(2)自润滑复合涂层

采用喷射电沉积在SLM铝合金表面制备Ni-MoS_(2)自润滑复合涂层。用摩擦磨损试验机评价镀液中MoS_(2)浓度对Ni-MoS_(2)自润滑复合涂层摩擦磨损性能的影响。结果表明:共沉积MoS_(2)微粒能有效降低Ni-MoS_(2)自润滑复合涂层的摩擦系数和磨损率。与纯Ni涂层相比,Ni-MoS_(2)自润滑复合涂层与316L钢球对磨的摩擦系数和磨损率显著降低,摩擦系数从0.51降至0.12,磨损率从0.41 mg/m降至0.11 mg/m,为SLM铝合金表面改善摩擦学性能提供了参考。

Al_(2)O_(3)浓度对柔性摩擦辅助电镀Ni-Co复合镀层性能的影响

利用柔性摩擦辅助电沉积在炮钢表面制备n-Al_(2)O_(3)/Ni-Co复合镀层,研究镀液中Al_(2)O_(3)浓度对Ni-Co复合镀层的组织结构和性能影响。结果表明,当Al_(2)O_(3)为5 g·L^(-1)时,镀层平均晶粒尺寸最小(9.6 nm),显微硬度最大(573.28 HV);腐蚀电化学研究表明,此时镀层自腐蚀电位正移至-0.304 V,自腐蚀电流较小(1.313μA·cm^(-2)),耐腐蚀性较好。

Ni-Sn/MoO_(2)复合电极的制备及析氢性能研究

在焦磷酸盐体系中,通过复合电沉积技术制备了Ni-Sn/MoO_(2)复合镀层,探究了MoO_(2)质量浓度对Ni-Sn/MoO_(2)复合镀层析氢性能和稳定性的影响。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、能量色散X射线谱仪(EDS)对复合镀层进行了物理表征。结果表明,MnO_(2)颗粒成功沉积到复合镀层中,并改变了Ni-Sn合金电极的组成和微观形貌。通过线性极化曲线(LSV)、塔菲尔曲线(Tafel)、电化学阻抗谱(EIS)、计时电位法(CP)对复合镀层的析氢性能和稳定性进行了测试,与Ni-Sn合金电极相比,MoO_(2)的加入有效地提高了Ni-Sn/MoO_(2)复合镀层的性能,在10 mA/cm^(2)极化电流密度下,MoO_(2)浓度为0.75 g/L时制备的复合镀层表现出最低的析氢过电位(296.91 mV),具有更高的析氢性能和稳定性。

占空比对脉冲电镀Ni-Co-Al_(2)O_(3)-WS_(2)复合镀层摩擦学性能的影响

为提高CrNi3MoVA钢的耐磨性能,用脉冲电沉积法在CrNi3MoVA钢表面制备了Ni-Co-Al_(2)O_(3)-WS_(2)复合镀层,利用扫描电镜(SEM)和X射线衍射仪(XRD)分析镀层的表面形貌和物相结构,用纳米压痕仪和往复式摩擦磨损试验机测试镀层的纳米力学性能与摩擦学性能。结果表明:Ni-Co-Al_(2)O_(3)-WS_(2)复合镀层表面呈结节状凸起,随着占空比的增加,镀层表面结节密度减少,(111)晶面择优取向更加明显。占空比为0.1的复合镀层拥有最高的硬度7.24GPa,最低的平均摩擦系数0.38和体积磨损率1.52×10^(-4) mm^(3)·(N·m)^(-1)。镀层中的n-Al_(2)O_(3)颗粒会支撑在摩擦面上减少摩擦副间的接触面积,同时与n-WS_(2)颗粒与在剪切作用下脱落形成润滑膜,发挥协同减磨作用提高镀层摩擦学性能。

超声波辅助铁基体电沉积Zn-Ni-P/纳米ZrO_(2)复合镀层及性能研究

通过电沉积并辅助超声波振荡在铁基体上制备出Zn-Ni-P/纳米ZrO_(2)复合镀层。研究了镀液中ZrO_(2)颗粒浓度对复合镀层中ZrO_(2)颗粒含量以及复合镀层表面形貌、相结构、硬度、耐磨性能和耐腐蚀性能的影响。结果表明:随着镀液中ZrO_(2)颗粒浓度从5 g/L增加至30 g/L,ZrO_(2)颗粒含量呈现先升高后降低趋势,复合镀层的形貌特征发生变化,导致硬度、耐磨性能和耐腐蚀性能存在差异,但不同复合镀层的相结构无明显差异,都含有单质Zn、Ni_(5)Zn_(21)和ZrO_(2)相。镀液中ZrO_(2)颗粒浓度为20 g/L时,复合镀层中ZrO_(2)颗粒含量达到10.43%,该复合镀层的晶粒细小且结合紧密,表现出良好的致密性,硬度达到503.5 HV,平均摩擦系数和磨损失重仅为0.48和3.42 mg,电荷转移电阻和低频端阻抗值分别达到6.34×10^(3)Ω·cm^(2)和6.84×10^(3)Ω·cm^(2),其性能与Zn-Ni-P合金镀层相比显著提高。适当增加镀液中ZrO_(2)颗粒浓度有利于提高复合镀层中ZrO_(2)颗粒含量,使复合镀层的晶粒明显细化且致密性改善,具有较强的阻碍局部塑性变形和承载能力,并且能有效抑制电化学腐蚀,从而表现出更好的性能。

Investigation on plasma-sprayed ZrO_2 thermal barrier coating on nickel alloy substrate

The thermal barrier coatings with NiCrAlY alloy bonding layer, NiCrAlY Y 2O 3 stabilized ZrO 2 transition layer and Y 2O 3 stabilized ZrO 2 ceramic layer are prepared on nickel alloy substrates using the plasma spray technique. The relationship among the composition, structure and property of the coatings are investiga ted by means of optical microscope, scanning electronic microscope and the experiments of thermal shock resistance cycling and high temperature oxidation resistance. The results show that the structure design of introdu cing a transition layer between Ni alloy substrate and ZrO 2 ceramic coating guarantees the high quality and properties of the coatings; ZrO 2 coatings doped with a little SiO 2 possesses better thermal shock resistance and more excellent hot corrosion resistance as compared with ZrO 2 coating materials without SiO 2 ;the improvement in performance of ZrO 2 coating doped with SiO 2 is due to forming more dense coating structure by self closing effects of the flaws and pores in the ZrO 2 coatings.

Corrosion Behavior of Electrodepositing Ni/Al_2O_3 Composite Coatings under the Presence of NaCl Deposit

The morphology and corrosion behavior of Ni/Al2O3 composite coatings prepared using double-pulsed electrodepositing technique after oxidized under 800 ℃ NaCl deposit in air environment were analyzed by scanning electrical microscope (SEM), X-ray diffraction(XRD) and energy dispersive spectrum(EDS). The results showed that the corrosion of all composite coatings was accelerated under NaCl deposits, and the corrosion products were rather porous with poor adherence to the matrix. Al2O3 particles in the coatings can refine the grain size and improve the high temperature corrosion resistance of the coatings. Within the test scope, the more Al2O3 particles in the coatings, the lower corrosion rates could be obtained, and the corrosion mechanism was also discussed.

XPS AND UPS STUDIES OF THE INTERFACIAL INTERACTION IN Ni ZrO 2 COMPOSITE PLATING

The interfacial interaction existing in the Ni ZrO 2 composite plating has been investigated. The experimental results show that no new phases were formed in the interfacial regions between matrix Ni and ZrO 2 particles, but an orbital interaction through the mutual overlap of the d orbits does exist in the interfacial regions between Ni atoms and Zr 3+ ions.

CeO_(2)对WC/Ni复合熔覆层微观组织与性能的影响

本工作采用真空熔覆技术制备了不同CeO_(2)含量的WC/Ni复合熔覆层,通过SEM、XRD、EDS及显微硬度计对复合熔覆层的微观组织、成分及硬度分布等进行系统分析。结果显示:与基体呈冶金结合的复合熔覆层组织致密,复合熔覆层由厚度2~3 mm且具有网状结构特征的复合层区与约300μm的过渡层区组成,根据熔合程度过渡区又分为冶金熔合区、扩散熔合区及扩散区;随着CeO_(2)含量的增加,复合熔覆层的晶粒逐渐细化、熔合质量提高,特别是过渡熔合区出现鱼骨状的析出相;复合区的网孔部位主要组成相为γ-(Ni,Fe)固溶体、FeNi_(3)、Cr_(7)C_(3)、Cr_(23)C_(6)、Ni_(3)Si和NiB,网线区主要组成相为WC、WC_(2)、γ-(Ni,Fe)固溶体、共晶组织等;复合熔覆层的显微硬度由表面至基体逐渐降低,且随着CeO_(2)含量的增加硬度逐渐升高,CeO_(2)含量为1.5%时,达到最大值,其平均显微硬度比基体提高5~6倍。

热处理温度对Ni-ZrB_(2)镀层微观组织与硬度的影响

采用电镀方法制备了Ni-ZrB_(2)复合镀层,研究了热处理温度对复合镀层物相、微观组织和显微硬度的影响。结果表明:未进行热处理时,Ni-ZrB_(2)复合镀层的表面粗糙、致密性差。经热处理后,复合镀层表面平整致密,热处理温度为400℃时,复合镀层的表面最为致密。添加ZrB_(2)粒子未改变镀层的晶体结构,但镀层的显微硬度得到提升。随着热处理温度的升高,镀层的显微硬度先升高后降低,当热处理温度为400℃时,镀层的显微硬度最高。

钛合金表面等离子喷涂 ZrO_2-NiCoCrAlY 梯度涂层的抗热震行为

ＺｒＯ２－ＮｉＣｏＣｒＡｌＹ梯度涂层的成分沿厚度方向呈连续梯度化分布，提高了涂层与基体的粘结强度和涂层的内聚强度，其抗热震性能优于双层涂层。在较大热冲击应力作用下，梯度涂层整体自基体表面剥落而失效；在较小热冲击应力作用下，由于ＮｉＣｏＣｒＡｌＹ底层与ＴＣ４合金基体发生了热相互作用，改善了涂层与基体的结合状况，梯度涂层纵向断裂并部分自基体表面剥落而失效。

Ni-ZrO_2复合电镀工艺的研究

研究了Ni ZrO2 复合镀液体系中微粒与镀液间的相互作用。镀液中的电解质NiSO4和NiCl2 对ZrO2 纳米微粒在复合镀液中的悬浮稳定性有很大影响。阴极极化曲线表明纳米微粒的加入改变了基质金属电沉积的过程。以高分子聚电解质作为分散剂 ,利用其在微粒之间形成的空间位阻效应 ,减弱镀液中离子对微粒的聚沉作用 ,得到了均匀分散的ZrO2 纳米微粒的复合镀镍溶液 。

Wear Performance of Ni/ZrO_2 Infiltrated Composite Layer

The Ni/ZrO2 was used as raw materials to fabricate the surface infiltrated composite layer with 1-4 mm thickness on cast steel substrate through vacuum infiltrated casting technology. The microstructure indicated that the infiltrated composite layer included surface composite layer and transition layer. Wear property was investigated under room temperature and 450 ~C. The results indicated that the abrasion volume of substrate was 8 times that of the infiltrated composite layer at room temperature. The friction coefficient of infiltrated composite layer decreased with the increasing load. The wear resistance of infiltrated composite layer with different ZrO2 contents had been improved obviously under high temperature. The friction coefficient of infiltrated composite layer was decreased comparing with that at room temperature. The oxidation, abrasive and fatigue abrasion was the main wear mechanism at room temperature. Oxidation abrasion, fatigue wear and adhesive wear dominated the wearin~ process under elevated temperature.

ZrO_2-Ni等离子喷涂涂层的残余应力

对不同镍含量的ＺｒＯ２－Ｎｉ等离子喷涂层采用Ｘ射线应力分析技术测试涂层表面应力，用曲率测试应力分析方法测定涂层平均应力，两者有较好的相关性，均表明涂层的残余应力为较小张应力。据测试的曲率半径估算了二层、三层、四层和六层阶梯涂层各层的平均残余应力和涂层喷涂的平均温度，结果表明多层过渡结构对改善涂层残余应力作用甚微，所估算的喷涂温度与实际操作条件基本相符。

Ni/ZrO2-SiO2催化剂催化乙酰丙酸加氢合成γ-戊内酯

分别以ZrO_2、SiO_2及ZrO_2-SiO_2复合氧化物为载体,采用等体积浸渍法制备了Ni含量为10%(质量分数)的催化剂,考察了其催化乙酰丙酸液相加氢性能。采用N2-物理吸附、NH3-TPD、H2-TPR、XRD、TEM等表征手段对催化剂进行了表征。研究结果表明,在所制备的催化剂上,乙酰丙酸先经C=O加氢生成4-羟基戊酸,后者快速脱水酯化为γ-戊内酯。Ni/ZrO_2-SiO_2催化剂较Ni/ZrO_2与Ni/SiO_2催化剂具有高的金属分散度和丰富的表面酸性中心,表现出高的C=O加氢活性以及优异的乙酰丙酸加氢合成γ-戊内酯性能。在反应温度为200℃,氢气压力4 MPa的反应条件下,乙酰丙酸的转化率达到100%,γ-戊内酯的选择性大于99.9%。

耐高温Ni-ZrO_2复合镀层的制备及影响因素研究

采用复合电沉积技术制备出了Ｎｉ－ＺｒＯ２耐高温复合镀层，并利用正交设计对影响复合电沉积过程的电流密度ｉ、镀液中微粒浓度ｃ、搅拌方式ｍ、微粒粒径ｄ及其间的交互作用等进行了研究。结果表明，上述因素对复合镀层中ＺｒＯ２含量影响显著性大小顺序为：ｄ＞ｍ＞ｄ×ｍ＞ｃ＞ｄ×ｃ＞ｉ×ｍ。

Ni-ZrO_2复合镀层形成过程的研究

采用复合电沉积技术制备出了Ｎｉ－ＺｒＯ２复合镀层，并利用正交设计对影响复合电沉积过程的有关因素（包括电流密度、ＺｒＯ２微粒粒径、搅拌方式、镀液中微粒含量及其间的相互作用）进行了系统研究，镀液中ＺｒＯ２微粒表面荷电状况的分析表明，ＺｒＯ２微粒表面由于吸附了溶液中的Ｎｉ２＋而荷正电。

ZrO_2MoSi_2Ni-Si-Mo FGM浸涂成形工艺

对采用粉浆浸涂工艺制备ZrO2 MoSi2 Ni Si MoFGM进行了研究。研究结果表明 ,采用粉浆浸涂成形ZrO2 MoSi2 Ni Si MoFGM时 ,每层预涂层的临界厚度为 2 5 0 μm ,临界提出速度为 0 0 5mm s。脱脂、烧结工艺为 :5℃ min升温到 2 80℃保温 10min ,1℃ min升温到 5 0 0℃保温 4h ,10℃ min升温到 130 0℃ ,5MPa热压 1h ;脱脂和烧结气氛为氩气气氛。