新型PEO/纳米结构ZrO_2镁合金涂层的抗菌活性及腐蚀行为（英文）

为了增强镁合金的耐腐蚀性和抗菌活性,先采用等离子体电解氧化(PEO)在镁合金上制备一层结合层,再用空气等离子喷涂(APS)制备纳米结构ZrO_2表面涂层。采用电化学试验研究涂层样品的腐蚀行为,采用琼脂扩散法对其进行大肠杆菌病原菌抑菌活性评价,并与无涂层样品进行对比。与PEO涂层和无涂层镁合金相比,PEO/纳米ZrO_2涂层样品的腐蚀电流密度最低,电荷传递阻力最高,相位角和阻抗模量最高。PEO结合涂层被纳米ZrO_2表面涂层完全密封,能够显著延缓侵蚀性离子向镁合金表面迁移,显著提高镁合金在模拟体液(SBF)中的耐蚀性。此外,PEO/纳米ZrO_2涂层的抗菌活性也高于PEO涂层和无涂层镁合金,这是由于ZrO_2纳米颗粒通过作用于细胞膜而降低了大肠杆菌的生长速率。     

ZrO2p包覆BN纳米涂层的固相反应合成及作用效果

采用固相反应合成工艺在纳米ZrO2颗粒(ZrO2p)上进行BN包覆处理,通过SEM,TEM,DSC等手段对颗粒包覆情况及其作用效果进行研究.表明以H38O3,CO(NH2)2为原料,二者摩尔比为13、按BN与ZrO2的体积比为31设计,于750℃下氮化处理,可在ZrO2纳米颗粒上成功包覆厚度约10～50 nm的非晶BN纳米层.复合粉体的热分析和热压烧结制备的ZrO2p/BN-SiO2复合陶瓷材料组织观察证实,该涂层可有效阻止ZrO2与SiO2之间发生反应.     

等离子喷涂纳米团聚体粉末的熔化特性研究

纳米陶瓷粉末(CYZ:ZrO2-4.5wt%Y2O3-25wt?O2和YSZ:ZrO2-8wt%Y2O3)经过团聚后,采用等离子喷涂(APS)方法在GH30高温合金表面制备热障涂层(TBC).用透射电镜(TEM)、扫描电镜(SEM)、场发射显微镜(FESEM)和X射线衍射仪(XRD)对团聚体粉末在等离子焰流中的熔化情况、制备的涂层组织结构进行了分析研究.结果表明:团聚后的球形粉末经过等离子弧后对于较大的团聚体颗粒只是表层约1μm被熔化,颗粒内部仍保持原始粉末的纳米结构;制备的涂层主要由熔化结晶部分和未熔化的纳米粒子构成,熔化结晶部分晶粒尺寸为60～80nm,大于原始粉末尺寸;CYZ涂层组成相为稳定的t相和c相,涂层中分布有大量的微裂纹和闭合的孔隙;两种涂层的孔隙率分别为6.2%和7.6%.     

纳米复合涂层ZrO2/0.05w(Al2O3)力学性能的Weibull分布特性

采用等离子喷涂方法制备了掺杂纳米Al2O3的ZrO2纳米陶瓷复合涂层（NCC）。并参照ZrO2传统涂层（MCC），探究了涂层显微硬度与微观组织结构的关系。试验数据显示，纳米复合陶瓷涂层表面与断面的平均显微硬度值均明显高于传统涂层；两者的Weibull分布均呈各向异性和分散性，但纳米复合陶瓷材料的分布较集中。通过TEM分析进一步表明，纳米复合涂层组织的明显细化、纳米Al2O3颗粒在ZrO2涂层中的弥散分布、微裂纹（微孔）韧化、晶内／晶间强化是NCC具有优异的力学性能的主要原因。     

AZ91和AZ80镁合金表面含石墨纳米颗粒的PEO涂层的摩擦和腐蚀行为（英文）

用等离子电解氧化(PEO)法在AZ91和AZ80镁合金表面制备涂层,研究在电解液中添加石墨纳米颗粒对涂层的耐腐蚀性和耐磨性能的影响。所用电解液为含有磷酸盐和硅酸盐的碱性溶液,并采用两种不同的PEO处理时间(1 min和3 min)。用动电位极化法和电化学阻抗谱(EIS)分析涂层的耐腐蚀性,用平面-盘式滑动摩擦实验测试其耐磨性能。用扫描电镜及能谱仪(SEM-EDS)观察涂层的组织形貌、微观结构、元素组成和涂层厚度。结果表明,石墨纳米颗粒增加了涂层的厚度,封闭了表面的孔隙,使涂层更致密,因此提高了其耐腐蚀性和耐磨性能。由于AZ91具有更高的铝含量,其耐腐蚀性能和耐磨性能的提高比AZ80更显著。     

热喷涂NiCr／纳米（ZrO2＋8％Y2O3）梯度涂层的性能研究

针对陶瓷涂层与基体结合强度低、易产生裂纹和剥落的现象,进行了抗高温氧化耐磨损梯度涂层的设计.采用热喷涂技术在45钢基体表面制备由面层[纳米(ZrO2 8%Y2O3)]和中间层(NiCr)组成的梯度涂层,利用扫描电镜(SEM)、测定结合强度、测定显微硬度、X射线衍射等方法研究涂层的性能.结果表明:NiCr/纳米(ZrO2 8%Y2O3)梯度涂层显微组织结构致密,与NiCr合金涂层和纳米(ZrO2 8%Y2O3)陶瓷涂层相比,具有更优良的力学性能;梯度涂层的面层有利于提高基体的耐高温、耐磨损性能,而中间层则有利于改善基体的抗高温氧化性能.     

改性纳米ZrO_2/环氧涂层的耐蚀性能研究

为了提高纳米材料在环氧树脂中的异相分散效果,采用十二烷基苯磺酸钠对自制纳米ZrO2表面进行修饰改性。采用XRD和FTIR技术对改性纳米ZrO2进行了表征,利用SEM/EDS观察了纳米ZrO2在环氧涂层中的分散效果,使用电化学阻抗谱技术研究了改性纳米ZrO2/环氧涂层对Q235钢的防护效果。结果表明:十二烷基苯磺酸钠成功接枝到纳米ZrO2表面,提高了纳米ZrO2在环氧树脂中的分散效果。环氧涂层的附着力随着纳米ZrO2含量的升高而降低,当纳米ZrO2在环氧树脂中的含量为1%时,涂层耐渗透性能好,涂层电阻大,对Q235钢防护性能最佳。     

CeO2掺杂对ZrO2-Y2O3纳米涂层性能的影响

在45钢基体表面等离子弧喷涂制备了掺杂不同含量CeO2纳米ZrO2涂层,运用XRD,SEM对涂层的组织结构进行了分析,测试了涂层的结合强度和显微硬度,考察了涂层与铝青铜对磨时的摩擦磨损性能．结果表明,CeO2增加了ZrO2涂层的致密性、结合强度和显微硬度．纳米ZrO2涂层中加入CeO2后,增加了ZrO2涂层／铝青铜摩擦副的摩擦系数,增强了纳米ZrO2涂层,耐磨能力．涂层与铝青铜对磨时,随着CeO2含量的增加,ZrO2涂层粘着磨损形式增强,而涂层脆性断裂脱落的趋势减轻．     

纳米ZrO2微粒对TC4合金表面微弧氧化陶瓷膜层耐蚀及耐磨性能的影响

目的 提高TC4微弧氧化表面陶瓷涂层的耐蚀性与耐磨性,并研究ZrO2微粒对涂层性能的影响。方法 在不同配比的硅酸钠、磷酸钠、氢氧化钠混合电解液中,通过微弧氧化技术在TC4钛合金表面制备陶瓷涂层,得到最佳电解液配比。将纳米ZrO2微粒添加到电解液中,以制备复合涂层。通过SEM、XRD、电化学工作站以及往复摩擦磨损试验机,研究不同含量ZrO2对膜层的形貌、相结构、耐腐蚀及耐磨性的影响。结果 随着纳米ZrO2浓度的增加,涂层微孔数量和尺寸都减小,膜层的主要组成相为ZrO2、ZrTiO4、TiO2、Ti2O、Al2O3和SiO2。0.9% NaCl溶液中的电化学极化曲线表明,随着ZrO2浓度的增加,涂层的自腐蚀电位不断提高,但当添加剂的含量达到12 g/L时,自腐蚀电位降低。摩擦磨损实验显示,不含ZrO2陶瓷膜层的比磨损率为1.082×10-3 mm3/(N?m),当ZrO2含量为9 g/L时,其比磨损率为3.489×10-4 mm3/(N?m),是未添加颗粒的32.24%。结论 纳米ZrO2微粒的加入有效提高了陶瓷涂层的耐蚀、耐磨性,特别地,当添加量为9 g/L时,涂层的耐蚀性耐磨性最好。     

溶胶-凝胶复合料浆热压滤法制备Al2O3-ZrO2-Y2O3复合涂层

在Fe-18Cr-8Ni不锈钢表面涂覆由纳米α-Al2O3颗粒、微米ZrO2-8wt%Y2O3(YSZ)颗粒和Al(OH)3-Y(OH)3溶胶-凝胶(sol-gel)组成的复合料浆层,采用热压滤法制备Al2O3-ZrO2-Y2O3复合涂层.为了匹配陶瓷涂层和金属基体间的热膨胀系数,采用sol-gel法在两者之间施加一层ZrO2-8wt%Y2O3过渡层.SEM分析结果表明,获得的陶瓷涂层厚度大于30μm,无裂纹.XRD分析结果表明,该陶瓷涂层主要由t-Zr0.92Y0.08O1.96和α-Al2O3以及少量t-ZrO2和γ-Al2O3相组成.900℃高温氧化实验结果表明,Al2O3-ZrO2-Y2O3复合涂层能够有效提高Fe-18Cr-8Ni基体的抗高温氧化和抗剥落性能.     

Thermal modeling of various thermal barrier coatings in a high heat flux rocket engine

One- and two-dimensional thermal models were developed to predict the thermal response of tubes with and without thermal barrier coatings (TBCs) tested for short durations in a H₂/O₂ rocket engine. Temperatures were predicted using median thermophysical property data for traditional air plasma sprayed ZrO₂–Y₂O₃ TBCs, as well as air plasma sprayed and low pressure plasma sprayed ZrO₂–Y₂O₃/NiCrAlY cermet coatings. Good agreement was observed between predicted and measured metal temperatures. It was also shown that the variation in the reported values of the thermal conductivity of plasma sprayed ZrO₂–Y₂O₃ coatings can result in temperature differences of up to 180°C at the ceramic/metal interface. In contrast, accounting for the presence of the bond coat or radiation from the ceramic layer had only a small effect on substrate temperatures (<20°C). The thermal models were also used to show that for the short duration test conditions of this study, a 100 μm thick ZrO₂–Y₂O₃ coating would provide a metal temperature benefit of approximately 300°C over an uncoated tube while a 200 μm thick coating would provide a benefit greater than 500°C. The difference in the thermal response between tubes and rods was also predicted and used to explain the previously-observed increased life of TBCs on rods over that on tubes.     

等离子喷涂La2(Zr0.7Ce0.3)2O7热障涂层的抗热震性能

采用等离子喷涂制备了La₂(Zr_0.7Ce_0.3)₂O₇（LZ7C3）热障涂层,并对涂层的微观组织、相结构、成分、相稳定性、涂层热导率以及抗热震性能进行了研究.结果表明,LZ7C3涂层由单相烧绿石结构物质组成,高温稳定性较好;涂层的热导率较块材下降约20%,这是由于涂层具有较高的孔隙率所致:涂层在不同温度范围的热震寿命和失效机制不同,在室温至约1000℃间的热震寿命为116 cyc,涂层失效方式以片状剥落为主:在室温至1100℃间的热震寿命为53 cyc,涂层失效方式为片状剥落和层状撕裂;在室温至1200℃间的热震寿命为3 cyc,涂层失效方式以层状撕裂为主.     

Thermal cycle behavior of plasma sprayed La2O3, Y2O3 stabilized ZrO2 coatings

The effects of La₂O₃ addition on thermal conductivity, phase stability and thermal cycle life of Y₂O₃ stabilized ZrO₂ plasma sprayed coatings were investigated. Although low thermal conductivity as well as high resistance to sintering was achieved by La₂O₃ addition, it tended to also result in lower phase stability and thermal cycle life of the coatings. Optimization of the composition and structure of the coatings improved these properties, and the optimized coatings showed prolonged thermal cycle life.     

Effects of plasma-sprayed NiCrAl/ZrO2 intermediate on the combination ability of coatings

A NiCrAl/ZrO₂ composite coating was deposited on the surface of metal carrier FeCrAl alloy by a plasma-spray technique. After static-state oxidation at 800°C, the transitions in structure and composition of the coating was analyzed by XRD, SEM and EDX. The results showed that the surface phases of the as-sprayed coating were mainly composed of Ni and ZrO₂. When the oxidation time was extended from 8 to 50 h, NiO crystallites were formed and these grew coarse on the coating surface, and alloy elements were diffused between the NiCrAl/ZrO₂ coating and the FeCrAl substrate. With the pretreatment, an intermediate coating was prepared with a coarse and porous structure, high cohesive strength and high heat resistance. These developed properties could provide high geometric surface area for a catalytic γ-Al₂O₃ washcoat, and enhance the adhesive strength between ceramic washcoat and metal substrate so as to extend the lifetime of the washcoat.     

Preparation and properties of a γ-Al2O3 washcoat deposited on a ceramic honeycomb

Washcoat deposited on ceramic honeycomb was prepared using pseudoboehmite, the CeO₂–ZrO₂–La₂O₃ solid solution, pore enlarger and other additives. The microstructures and surface performances of washcoat/honeycomb were investigated by SEM, BET surface area, XRD, ultrasonic vibration and hot shock simulation. The results show that the performance and loading of washcoat are affected obviously by the properties of slurry gel, such as the apparent viscosity, solid content, particle size and its distribution. When the apparent viscosity of slurry is lower, the gel with a narrow particle size distribution and finer particles can be obtained, with which the coating having an excellent performance can be prepared. Adding a small quantity of the CeO₂–ZrO₂–La₂O₃ solid solution can promote the thermal stability of washcoat, such as, after calcined at 1000 °C for 5 h the sample exhibits mainly the γ-Al₂O₃ phases and the θ-Al₂O₃ -Al₂O₃ and κ-Al₂O₃ phases have not been detected in the XRD spectra. It is found also that the washcoat prepared has excellent properties of the vibration-resistant, heat-resistant and its BET surface area reaches 50 m²/g.     

Preparation of ceramic coatings on inner surface of steel tubes using a combined technique of hot-dipping and plasma electrolytic oxidation

A new method for inner surface modification of steel tubes, named a combined technique of hot-dipping and plasma electrolytic oxidation (PEO) was proposed and demonstrated in this paper. In this work, metallurgically bonded ceramic coatings on inner surface of steel tubes were obtained using this method. In the combined process, aluminum coatings on steel were firstly prepared by the hot-dip process and then metallurgically bonded ceramic coatings were obtained on the aluminum coatings by PEO. The element distribution, phase composition and morphology of the aluminide layer and the ceramic coatings were characterized by SEM/EDX and XRD. The corrosion resistance of the ceramic coatings were also studied. The results show that, after hot-dip treatment, the coating layers consist of two layers, where Al, Fe_xAl _(1−x) were detected from external topcoat to the aluminide/steel substrate. Then after PEO process, uniform Al₂O₃ ceramic coatings have been deposited on inner surface of steel tubes. The ceramic coatings are mainly composed of -Al₂O₃ and γ-Al₂O₃ phase. The compound coatings show favorable corrosion resistance property. The investigations indicate that the combination of hot-dipping and plasma electrolytic oxidation proves a promising technique for inner surface modification of steel tubes for protective purposes.     

脉冲频率对铝基PEO涂层隔热性能的影响规律及作用机理

在硅酸盐体系下使用等离子体电解氧化(PEO)技术在ZL109铝合金试样表面进行了陶瓷化处理,并采用SEM、XRD、DSC、激光导热仪等方法系统地研究了脉冲频率变化对PEO涂层热性能的影响规律及作用机理。研究表明,脉冲频率主要通过影响涂层的相结构组成及显微结构从而引起隔热性能的变化。当频率为200 Hz时,PEO涂层的热导率最低,为0.113 W/(m·K)。     

硅酸盐体系电解液中添加Na2WO4对LY12铝合金陶瓷膜性能的影响

通过SEM、XRD、硬度试验、电化学腐蚀试验研究了在硅酸盐体系电解液中加入不同浓度的Na2WO4对LY12铝合金微弧氧化陶瓷膜表面形貌及性能的影响.结果表明,添加Na2WO4改变了膜层的微观结构,使微弧氧化膜层硬度增加,表面平滑,呈现出小而少的孔洞结构,且表面堆积少量形状不规则的白色质点;随着Na2WO4添加量的增加,...     

Thermoelectric properties of Fe0.98Co0.02Si2 with ZrO2 and rare-earth oxide dispersion by mechanical alloying

The n-type Co-doped β-FeSi₂ (Fe_0.98Co_0.02Si₂) with dispersion of several oxides, such as ZrO₂ or several rare-earth oxides (Y₂O₃, Nd₂O₃, Sm₂O₃ and Gd₂O₃), was synthesized by mechanical alloying and subsequent hot pressing. The effects of these oxide dispersions on the thermoelectric properties of Fe_0.98Co_0.02Si₂ were investigated. ZrO₂ was decomposed in the β phase, and the ZrSi and -FeSi phases, which are metallic phases, were formed in the samples with ZrO₂ addition. The Seebeck coefficient and the electrical resistivity were significantly decreased with increasing amount of ZrO₂, indicating that a part of the Zr atoms was substituted for Fe atoms in the β phase. In the case of the samples with rare-earth oxide addition, a decomposition of a large amount of these added oxides did not occur. However, the rare-earth oxide addition caused a slight increase in the amount of the phase. The Seebeck coefficient was significantly enhanced by the rare-earth oxide addition especially in the low temperature range. These facts indicated that a small amount of rare-earth oxides was decomposed in the β phase, and rare-earth elements were substituted for Fe atoms as a p-type dopant, resulting in the decrease in the carrier concentration. The rare-earth oxide addition was also effective in reducing the thermal conductivity.     

B2O3含量对SiO2–B2O3–Al2O3–Na2O系陶瓷结合剂结构与性能的影响

制备不同B₂O₃含量的SiO₂–B₂O₃–Al₂O₃–Na₂O系玻璃试样和陶瓷结合剂试样,利用电子多功能实验机、扫描电镜、显微硬度仪、平面流淌法、热膨胀系数测试仪等分别测试不同玻璃试样的密度和显微硬度,陶瓷结合剂试样的抗折强度、微观形貌和热膨胀系数等,并用X射线衍射仪、傅里叶变换红外光谱仪对陶瓷结合剂的结构和成分变化进行分析。结果表明:将B₂O₃引入陶瓷结合剂中可有效降低其烧结温度,提高其热稳定性并调节其热膨胀系数等。在陶瓷结合剂中加入摩尔分数为15%的B₂O₃时,其样条抗折强度最高为78.11 MPa,密度和硬度最高分别为2.45 g/cm3和856 MPa,且该陶瓷结合剂的热膨胀系数与金刚石最匹配。X射线衍射分析结果表明陶瓷结合剂是典型的玻璃相结构,且对磨料有良好的包覆效果。