Tribological Behavior of Nano-ZrO2 Reinforced PTFE-PPS Composites

Polytetrafluoroethylene (PTFE) is a commonly used seal material for oil-free engine that is well known for its excellent tribological properties. In this work, the nano-ZrO2 particles were used as the friction modifiers to improve the friction and wear performance of PTFE-PPS composites. The friction and wear characteristics of PTFE/PPS-nano-ZrO2 composites were investigated by a block-on-ring tester under dry friction sliding condition. The worn surfaces, counterpart transfer films and wear debris were studied by scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that the increase of nano- ZrO2 content could effectively reduce the coefficient of friction and enhance the anti-wear ability of PTFEPPS composites. Especially, the best tribological properties of the composites were obtained when the particle content of nano-ZrO2 was 10 vol%, the anti-wear performance of composite is 195 times better than that of the unfilled PTFE-PPS composite. Under different conditions, the coefficient of friction of PTFE/PPS-nano-ZrO2 composites was more affected by the applied load while the wear rate was more affected by the sliding velocity.

Tribological Behaviours of PTFE Composites Filled with PEEK and Nano-ZrO2 Based on Pin-on-Flat Reciprocating Friction Model

Nano-ZrO2 and PEEK particles were synergistically filled in unfilled PTFE to improve the wear resistance and maintain a relatively low friction coefficient,and the materials were studied using a reciprocating sliding friction and wear tester.In the friction tests,the evolution of various tribological characteristics in both the contact interfaces and debris was observed,and the wear mechanism of the PTFE composites was investigated.The results showed that the wear rate of the PTFE composites synergistically filled with nano-ZrO2 and PEEK was lower and its friction coefficient was slightly higher than that of the unfilled PTFE;the uniformity and continuity of the transfer film generated by the composite with nano-ZrO2 and PEEK were the best,and the particle size of the debris was minimal in comparison to that in other sample systems.

火焰喷涂PA1010/nano-ZrO_2复合涂层的非等温结晶动力学

利用火焰喷涂法制备了聚酰胺1010(PA1010)/纳米氧化锆(nano-ZrO2)复合涂层。采用示差扫描量热法(DSC)研究其非等温结晶行为,对所得的数据分别用Jeziorny法、Ozawa法和Mo法进行处理。结果表明,用Jeziorny法和Mo法处理非等温结晶过程比较理想,而Ozawa法不适用。用Jeziorny法求出的参数Zc(结晶速率常数)和n(Avrami指数)均随降温速率的增加而增加;nano-ZrO2的加入使复合涂层的Zc和n略大于纯PA1010涂层;并使复合涂层结晶半衰期降低、结晶速率及结晶度增大。表明nano-ZrO2具有明显的成核剂作用,加快PA1010的结晶速率,提高涂层的结晶度。

纳米ZrO2对热喷涂尼龙1010涂层非等温结晶与熔融行为的影响

利用火焰喷涂法制备了尼龙1010(PA1010)/n-ZrO2复合涂层,采用差示扫描量热法(DSC)对复合涂层的非等温结晶过程、熔融行为进行了分析。结果表明,纳米ZrO2粒子的加入不仅能提高复合涂层的结晶速率和结晶温度,而且使复合涂层的熔融峰肩峰的熔融温度高于纯PA1010涂层。结论:纳米ZrO2粒子具有成核剂的作用,诱导尼龙大分子结晶,使其结晶能力及结晶的完善程度提高。

纳米ZrO2和聚醚醚酮填充聚四氟乙烯的摩擦学性能基于环-块摩擦模型的演变过程

用不同体积分数的纳米ZrO2和聚醚醚酮(PEEK)颗粒填充改性聚四氟乙烯(PTFE)复合材料。使用环-块摩擦磨损试验机测试PTFE复合材料在滑动速度为2 m/s、载荷为200 N的试验条件下的摩擦学性能。获取不同阶段摩擦学性能的数据,计算出在整个试验过程中样品的瞬时磨损率。利用扫描电镜观察不同试验阶段对偶钢环表面形貌的变化图像并进行分析。利用仿真模拟软件(ABAQUS)对摩擦过程中PTFE复合材料的接触应力变化进行分析。结果表明,纳米ZrO2和PEEK颗粒可以协同改善PTFE复合材料的摩擦学性能。特别是添加8%的纳米ZrO2和20%的PEEK能使PTFE复合材料同时获得最佳的耐磨性(1.29×10-6 mm3/Nm)和较低的摩擦系数。在摩擦试验的后期PTFE复合材料的瞬时磨损率突然急剧上升。根据瞬时磨损率、磨损表面、转移膜形貌和磨屑形态特征的变化规律,将整个磨损过程分为3个阶段(低磨损阶段、过渡磨损阶段和严重磨损阶段)。

Ti/nanoTiO_2-ZrO_2修饰电极电催化氧化葡萄糖

在无水乙醇和乙酰丙酮混合溶液中,电解Ti金属制得前驱体Ti(OCH2CH3)(4-y)(acac)y,再加入ZrCl4,将上述溶液直接水解、干燥后在450℃煅烧2h,粉体通过X射线衍射(XRD)分析表明:纳米TiO2-ZrO2粉体呈单分散结构。通过凝胶涂抹、煅烧得到高活性的Ti/nanoTiO2-ZrO2修饰电极,电子透射显微镜(TEM)测试表明,颗粒平均尺寸为30～40nm。通过循环伏安研究发现,Ti/nanoTiO2-ZrO2电极对葡萄糖氧化具有高催化活性。

LiNO3熔盐辅助煅烧制备高分散纳米ZrO2粉体

以可溶性锆盐溶液反向滴定氨水溶液成功地制备了纳米ZrO2粉体,系统研究了反应物浓度与煅烧温度对产物粒径和形貌的影响;在反应过程中加入表面活性剂,并采用正丁醇共沸蒸馏干燥和LiNO3熔盐辅助煅烧等方法,以控制粒径、减少团聚。通过热重-差热分析(TG-DTA)、透射电镜(TEM)、X射线衍射(XRD)、比表面积分析(BET)等对样品进行了形貌表征、晶型及粒径分析。结果表明:上述多种方法联合使用能够有效控制粒径、减少团聚,制备出的纳米ZrO2粉体分散性优异,为立方晶相结构,粒径15nm左右。

Catalytic combustion of methane over nano ZrO_2-supported copper-based catalysts

The nano ZrO2-supported copper-based catalysts for methane combustion were investigated by means of N2 adsorption, TEM, XRD, H2-TPR techniques and the test of methane oxidation. Two kinds of ZrO2 were used as support, one （ZrO2-1） was obtained from the commercial ZrO2 and the other （ZrO2-2） was issued from the thermal decomposition of zirconium nitrate. It was found that the CuO/ZrO2-2 catalyst was more active than CuO/ZrO2-1. N2 adsorption, H2-TPR and XRD measurements showed that larger surface area, better reduction property, presence of tetragonal ZrO2 and higher dispersion of active component for CuO/ZrO2-2 than that of CuO/ZrO2-1. These factors could be the dominating reasons for its higher activity for methane combustion.

碳钢表面Fe-W-ZrO2纳米复合电沉积层的组织结构分析

采用复合电沉积方法,在碳钢表面制备了质量组成为的Fe 38.3%、W 52.7%、ZrO29%的Fe-W-ZrO2纳米复合镀层,研究了ZrO2纳米微粒、热处理对镀层组织和结构的影响。结果表明,弥散分布的ZrO2纳米微粒对Fe-W基质镀层的结构有明显影响,镀态下Fe-W-ZrO2纳米复合镀层内部结构致密无裂纹,呈明显非晶态结构特征;经500℃热处理后,复合镀层开始晶化析出-αFe相,随着热处理温度升高,晶化相不断析出并长大,700℃时复合镀层晶化已基本完成,M6C型碳化物F3W3C相出现,与-αFe相两相并存,继续加热至800℃时,F3W3C成为涂层主相。

热处理对Fe-W-ZrO2纳米复合镀层结构和性能的影响

采用复合电沉积方法,在碳钢表面制备质量分数为Fe38.3%、W52.7%、ZrO29%的Fe-W-ZrO2纳米复合镀层,研究热处理对镀层结构和性能的影响。结果表明,镀态下Fe-W-ZrO2纳米复合镀层内部结构致密无裂纹,呈明显非晶态结构特征,具有较高的硬度和耐磨性;复合镀层经500℃热处理后开始晶化,随温度升高,镀层晶化析出α-Fe相,硬度、耐磨性继续提高;700℃时复合镀层晶化完成,M6C型复合碳化物Fe3W3C析出,与α-Fe相两相并存,镀层硬度、耐磨性急剧增大,到800℃时,Fe3W3C硬质相逐渐成为主相,硬度达到最高点1270HV,耐磨性是镀态下的5～7倍;而且纳米微粒ZrO2的引入不会在Fe-W非晶合金镀层中形成新相,在适当的热处理下能有效提高Fe-W-ZrO2纳米颗粒复合镀层的硬度、耐磨性。

ZrO2纳米粉对Al-Si合金微弧氧化陶瓷层组织和性能的影响

为提高铝硅合金在高温环境下的服役寿命,文中通过微弧氧化技术在硅酸盐体系电解液中于Al-Si合金表面制备ZrO2-Al2O3陶瓷层。采用扫描电子显微镜和X射线衍射仪分别对陶瓷层进行了表面、截面形貌以及物相组成分析。利用涡流测厚仪测量不同ZrO2加入量的膜厚,分析ZrO2-Al2O3体系陶瓷层的生长速率,通过自制隔热装置对陶瓷层进行隔热性能测试。研究结果表明:Al2O3陶瓷层表面由许多胞状熔融物烧结而成,粗糙度较大,并分布着孔洞较大的放电通道,膜厚约10μm;ZrO2-Al2O3陶瓷层表面除了胞状熔融物还有细小的颗粒,粗糙度较小,且陶瓷层更加致密,膜层厚度达到25μm。两种体系陶瓷层均形成了Al2O3及SiO2相,且在15°~50°范围内出现"馒头包"现象,说明陶瓷层中有非晶成分,但ZrO2-Al2O3陶瓷层中衍射峰"馒头包"的现象更为严重,非晶成分含量更高,说明在微弧氧化过程中ZrO2纳米粉的加入有利于亚稳相γ-Al2O3的形成。陶瓷层生长速度研究结果表明,电解液中ZrO2的浓度越大,陶瓷层厚度越厚,生长速度先增大后减小。隔热性能测试结果显示,随ZrO2含量的增多,陶瓷层的隔热温度升高,ZrO2的加入对涂层的隔热起到增强的作用。

纳米ZrO2对水泥基材料性能的改性作用

为了研究纳米ZrO2对水泥基材料抗压强度、孔隙率和渗透性能的改性作用,以30nm ZrO2为研究对象,研究纳米ZrO2掺量(1%、2%、4%、8%)对水泥基材料性能的影响,并分析其作用机制。试验结果表明,纳米ZrO2掺量为1%、2%、4%、8%时,水泥基材料的化学收缩约为对照组的87.7%、98.4%、117.1%、117.6%;抗压强度约提高了53%~135%;孔隙率和渗透系数分别降低5.4%~19.9%、7.9%~17.3%。综合分析发现,纳米ZrO2的作用机制主要是填充效应和晶核作用,即通过填充作用,降低了孔隙率达到提高抗压强度和降低渗透性能的目的;同时通过晶核作用加速了水泥的水化。

ZrO2对Ni-CeO2-ZrO2纳米复合电铸层组织结构及性能的影响

采用纳米复合电铸工艺制备Ni-CeO2-ZrO2纳米复合电铸层。研究镀液中ZrO2纳米微粒对复合电铸层中CeO2与ZrO2纳米微粒的质量分数的影响,测试和分析ZrO2对Ni-CeO2-ZrO2复合电铸层的表面形貌、结晶取向和显微硬度的变化。结果表明:合理选择ZrO2纳米微粒添加量,可以提高两种微粒在电铸层中的质量分数,能够促进CeO2纳米微粒与ZrO2纳米微粒共沉积。添加ZrO2纳米微粒后,可以获得晶粒较小、组织均匀的Ni-CeO2-ZrO2电铸层表面形貌,其结晶取向有所改善,显微硬度明显提高。

基于石墨烯/纳米ZrO2复合膜修饰电极测定苹果中残余对硫磷的研究

石墨烯作为“明星材料”,具有高导电性和高比表面积;二氧化锆对磷酸基团具有很好的吸附作用.将石墨烯和纳米二氧化锆分散液修饰到电极表面制备成一种纳米石墨烯/纳米ZrO2复合膜修饰的对硫磷电化学传感器,并对修饰剂的浓度、支持电解质的选择、溶液pH值、富集时间和富集电位等实验条件进行了优化.由于复合膜修饰电极综合了石墨烯的高导电性与纳米ZrO2的强吸附能力,对硫磷在修饰电极表面表现出富集时间短、电子转移速率快的特点.差分脉冲伏安法分析结果显示对硫磷在传感器上的氧化峰电流与其浓度在0.05~30μmol·L^-1范围内呈良好的线性关系,检测限达20 nmol·L^-1.用加标回收法测量苹果样品中对硫磷含量,回收率为99.1%~103.6%.

共沉淀法制得的CeO2／ZrO2纳米复合粉末的研究

采用化学共沉淀法制得了氧化铈摩尔含量在2％-12％之间的CeO2／ZrO2复合纳米粉体。研究了随着氧化铈含量的增加，氧化锆组分由单斜相（m）到四方相（t）转变的过程，并分析了影响相变的主要因素。从X射线衍射图谱（XRD）和透射电镜图（TEM）可以得出：随着氧化铈摩尔含量的增加，氧化锆四方相体积分数也随之增加，二者基本呈线性关系，当氧化铈含量为12mol％时，氧化锆在室温下被完全稳定在四方相，离子置换固溶体的形成是使四方相稳定在室温下的主要原因。

ZrO2纳微米纤维自增韧Al2O3陶瓷力学测试与断裂分析

通过对原位生长ZrO2纳微米纤维自增韧Al2O3基陶瓷的三点弯曲、单边切口梁与Vickers压痕测试,发现陶瓷硬度、弯曲强度与断裂韧性在ZrO2质量分数为35%时出现极大值.经SEM观察与XRD分析,发现裂纹扩展主要受含ZrO2纳微米纤维的α-Al2O3基棒晶控制,诱发裂纹偏转增韧机制,并伴随着相变增韧机制.

基于γ-Al2O3-ZrO2-ThO2的Pd基催化剂载体制备及应用

设计了一种用于负载型Pd基催化剂的γ-Al2O3-ZrO2-ThO2纳米管阵列载体。原位生长法制备的纳米孔Al2O3陶瓷模板经化学沉积形成γ-Al2O3-ZrO2-ThO2纳米载体,并以此纳米载体作为活性组分制备了具有高催化氧化活性的Pd催化剂。电镜结果表明,催化剂组分Pd能够均匀分散于纳米载体中。实验表明采用以γ-Al2O3-ZrO2-ThO2纳米材料为Pd基催化剂载体的CH4传感器具有较好的线性度和快速响应特性。

Effect of Nano-ZrO_2 on Microstructure and Thermal Shock Behaviour of Al_2O_3/SiC Composite Ceramics Used in Solar Thermal Power

The Al2O3-ZrO2（3Y）-SiC composite ceramics used in solar thermal power were prepared by micrometric Al2O3,nano-ZrO2 and SiC powders under the condition of pressureless sintering.The bulk density and bending strength of samples with 10vol% nano-ZrO2 sintered at 1480℃ were 3.222 g/cm3 and 160.4MPa,respectively.The bending strength of samples after 7 times thermal shock tests （quenching from 1000℃ to 25℃ in air medium） is 132.0MPa,loss rate of bending strength is only 17%.The effect of nano-ZrO2 content on the microstructure and performance of Al2O3-ZrO2（3Y）-SiC composite ceramic was investigated.The experimental results show that the bending strength of samples with above 10vol% nano-ZrO2 content has decreased,because the volume expansion resulting from t-ZrO2 to m-ZrO2 phase transformation is excessive;Adding proper nano-ZrO2 would be contributed to improve the thermal shock resistance of the composite ceramics.The Al2O3-ZrO2（3Y）-SiC composite ceramic has promising potential application in solar thermal power.

Structure and Performance of Ce-nano PO_4^(3-)/ZrO_2 Solid Acid Catalyst for Producing Biodiesel

The biodiesel prepared from Xanthoceras Sorbiflia Bunge Oil catalyzed by Ce doped nano PO_4^(3-)/ZrO_2 was investigated. A maximum biodiesel yield of 91.83% was achieved at the concentration of Ce^(3+) up to 0.1 mol/L, calcination temperature 500 °C, calcination time 3.0 h, and the concentration of phosphoric acid of 3.5 mol/L. Ce-nano PO_4^(3-)/ZrO_2 catalyst activities were correlated with the observed physico-chemical characteristics derived from scanning electron microscopy(SEM), FT-infrared(FT-IR), X-ray diffraction(XRD), thermogravimetric(TG) and Brunauer-Emmett-Teller(BET) analysis. The delayed crystallization of ZrO_2 made surface oxides have more defects which were beneficial to the adsorption of PO_4^(3-) by the concentration increment of Ce^(3+). The chemical composition of synthesized biodiesel was confirmed by gas chromatography(GC). The characteristics of Xanthoceras Sorbiflia Bunge oil were found within the optimal range in accordance with Chinese No. 0 diesel standard as a substitute diesel fuel.

REOx掺杂的ZrO2催化剂催化羟乙基吡咯烷酮脱水反应性能

催化剂在 N-( 氢氧根乙醇) 的脱水起一个重要作用 pyrrolidone (NHP ) 到准备 N-vinyl-pyrrolidone (NVP ) 。目前， NVP 产量仅仅在商业 ZrO2 催化剂上是大约 30% 。A coupled 降水和固态分散体技术被设计准备 nano-ZrO2 催化剂，在稀土元素，金属氧化物(REOx ) 被用作电子倡导者。结果显示催化剂做了 REOx (S-1.0 ) 以中等条件展出 NHP 脱水的最佳性能。NHP 变换和 NVP 选择是分别地 97.0% ， 82.3% 。特殊兴趣中是催化剂(S-1.0-1.0 ) 的索引分别地直到 98.4% 和 89.2% 。而且，这催化剂忍受好稳定性。它意味着 nano-ZrO2 做了 REOx 催化剂力量是为 NHP 脱水的潜在的商品催化剂。