Si0，含量对绿色荧光粉包膜效果的影响

采用溶胶-凝胶法对绿色荧光粉铝酸锶进行了SiO2包膜处理,并对膜层进行了X射线衍射(XRD)、耐水性和发光性能的测试.结果表明:SiO2含量对包膜效果有着重要的影响.SiO2含量太低,其耐水性受到限制,很容易发生水解;SiO2含量太高,影响其发光性能,发光亮度降低.通过试验对比发现,要想得到包膜效果较好的产品,SiO2与铝酸锶的质量比最好控制在10%～25%之间.     

溶胶—凝胶法制备的纳米SiO2对铝酸锶的包覆研究

碱土铝酸盐发光材料在水中或湿度较高的环境中常达不到发光要求。用溶胶—凝胶法制备的纳米SiO2对碱土铝酸盐系的铝酸锶进行表面包覆处理,可有效提高荧光粉的抗水解性能,使铝酸锶具有较好的蓄光、耐水效果。实验采用溶胶—凝胶法在铝酸锶表面包覆SiO2膜,并根据对包覆时不同温度、不同溶液pH值、不同陈化时间一系列条件下的耐水性和形貌分析,得到膜层各个环节最适条件为:温度80℃、溶液pH值为10、陈化时间48 h。     

CVD法在电致发光粉表面包覆SiO2膜

以硅酸乙酯和氧气作为前驱体,在500℃下, 采用流态化CVD法,对ZnS:Cu电致发光粉表面包覆SiO2薄膜,对膜层进行了SEM、EDX、AgNO 3抗腐蚀、发光亮度等测试.结果显示:发光粉颗粒表面明显存在一定量的SiO2.包覆的发光粉耐AgNO3腐蚀时间能达121h之久,样品的初始发光亮度均能达到未包覆样品的70%以上,包膜样品的发光光谱峰没有产生大的移动.     

包覆型ZrO2复合Al2O3基陶瓷

用表面被覆3 mol%Y2O3的纳米ZrO2复合Al2O3基陶瓷,研究包覆型ZrO2对Al2O3基陶瓷显微结构及对力学性能的影响.包覆型纳米ZrO2的加入,可改善Al2O3基陶瓷的显微结构.在ZrO2加入量达到9ψ/%时,ZrO2可有效阻碍Al2O3晶粒的异常长大,获得了细晶结构的陶瓷材料.包覆型ZrO2复合Al2O3基陶瓷材料的韧化机制不同于微米级ZrO2复合的材料,主要是通过残余应力场增韧,而不是相变增韧.     

金红石型TiO2的氧化硅膜包覆及其动力学研究

目的 研究以液相沉淀法制备硅包膜钛白粉(SiO2@TiO2)及氧化硅在TiO2粒子表面的沉积成膜过程动力学,从而指导钛白粉表面改性工艺的优化。方法 以硅酸钠为包膜剂在TiO2表面包覆氧化硅膜层,通过比表面积、Zeta电位、SEM和酸溶率分析,研究包膜温度、包膜pH、熟化时间等工艺条件对SiO2@TiO2膜层结构的影响。采用动力学模型对氧化硅在TiO2粒子表面的反应成膜过程进行计算拟合。结果 在包膜温度368 K、包膜pH=9.0以及反应熟化时间180 min时,获得的SiO2@TiO2氧化硅膜层致密性好,酸溶率稳定在14%的较低水平,比表面积保持在10.58 m²/g,等电点维持在2.34。氧化硅在TiO2粒子表面的成核点形成阶段的活化能为16.31 kJ/mol,生长成膜阶段的活化能为25.80 kJ/mol。结论 提高反应温度、在弱碱性条件下、延长熟化时间可使制备的SiO2@TiO2膜层致密性提高;SiO2@TiO2的比表面积、等电点与反映SiO2@TiO2膜层致密程度的酸溶率具有高度的相关性;氧化硅膜层在TiO2表面的包覆过程分为成核点形成以及氧化硅沉积成膜两个阶段,均符合三级反应动力学特征。     

彩色铝粉Fe2O3/SiO2/Al的液相沉积制备与表征

采用分步液相沉积法在片状铝粉表面包覆SiO2与Fe2O3双层薄膜制备了具有金属光泽的彩色铝粉,以彩度与光泽度为主要评价指标,探讨Fe2O3用量与pH值对铝粉包覆效果的影响,利用原子力显微镜(AFM)、扫描电子显微镜(SEM)和X射线衍射(XRD)等手段对包覆前后的铝粉进行表征.结果表明:当SiO2包覆量为20％(质量分数)时,随着Fe2O3膜厚的增加,铝粉颜色由浅黄→金黄→红黄过渡,光泽度下降;当m(Fe2O3)∶m(SiO2)∶m(Al)=0.75∶0.2∶1时,铝粉具有良好的彩度与光泽度,铝粉表面粗糙度由5.05 nm增大到20.6 nm;反应过程pH值对Fe2O3包覆效果有重要影响,pH值宜控制在3.9～4.0;表面活性剂PVP的加入有利于提高Fe2O3膜层与SiO2和Al基体的结合力,从而提高颜色稳定性.     

SiO2包覆对稀土磷光粉在涂层中发光性能的影响

摘 要: 为了防止稀土磷光粉在复合涂层中的发光猝灭,利用溶胶-凝胶法对稀土磷光粉SrAl2O4:Eu2+,Dy3+进行表面包覆,制备SiO2- SrAl2O4包覆粉体,再用冷喷涂技术在45#钢基体上制备Cu-14Al-X/SrAl2O4（未包覆/包覆）复合涂层,通过发光现象实现对涂层摩擦磨损状况的监测。采用SEM、激光粒度分析等技术对包覆粉体进行表征,再结合EDS、F97 Pro荧光分光光度计等研究和检测复合涂层微观组织、微区成分及其发光性能,探究冷喷涂过程中磷光粉的发光猝灭机理及SiO2包覆防猝灭工艺效果。结果表明,稀土磷光粉与Fe、Mn、Ni等金属元素接触以及喷涂粒子相互高速撞击是造成冷喷涂层发光性猝灭的主要原因。溶胶-凝胶法能够制备具有核-壳结构SiO2-SrAl2O4包覆粉体,形成的SiO2壳层结构较好地改善了粉体表面形貌,使得包覆粉体表面较为平整圆润,硬度明显增大,涂层组织过渡良好,发光性能更优。     

Sr_2Al_(14)O_(25):Eu~(2+),Dy~(3+)的共沉淀-水热合成及其发光性能

以氨水或碳酸铵为沉淀剂,采用共沉淀-水热合成法制备稀土掺杂铝酸锶发光纳米材料,并优化制备稀土掺杂铝酸锶发光材料的工艺条件。对激活剂、助激活剂、助熔剂的用量、体系的酸碱度和灼烧温度对目标产物发光性能的影响规律进行研究。结果表明:目标产物Sr2Al14O25:Eu2+,Dy3+属正交晶系,为蓝绿色长余辉纳米材料,主激发峰均在360 nm左右;氨水共沉淀法制备的产物主发射峰在490 nm,磷光衰减寿命约30 s;碳酸铵沉淀法制备的产物主发射峰在460 nm,磷光衰减寿命约15 s。     

SiO2包覆对含微量CO氢环境中LaNi4.25Al0.75吸氢动力学性能的影响

采用气相二氧化硅法制备了LaNi4.25Al0.75/SiO2复合材料,研究了该复合材料表面形貌以及氢中微量CO对LaNi4.25Al0.75合金及LaNi4.25Al0.75/SiO2复合材料吸氢动力学性能的影响。结果表明：合金被毒化后,在表面生成含NiO、La(OH)3、La2O3、Al(OH)3的氧化层,并且吸附大量CO,导致合金的吸氢量减少,动力学变慢。表面包覆SiO2可显著改善合金抗毒化性能     

溶胶凝胶法制备SiO2包覆Fe85Si9.6Al5.4软磁复合粉末

采用溶胶凝胶法,通过控制正硅酸乙酯(TEOS)和3-氨丙基三乙氧基硅烷(APTES)偶联剂的加入量,在Fe85Si9.6Al5.4粉末表面包覆SiO2绝缘层。采用X射线衍射(XRD)、傅氏变换红外光谱(FTIR)、X射线光电子能谱(XPS)、扫描电镜(SEM)和磁力显微镜(MFM)对粉末的微观结构及成分进行表征,采用振动样品磁强计(VSM)测试粉末的磁性能。结果表明:利用硅烷偶联剂对Fe85Si9.6Al5.4粉末表面改性后再加入TEOS,能在Fe85Si9.6Al5.4粉末表面包覆一层约1~2μm厚的絮状非晶SiO2;随着TEOS和APTES添加量的增多,SiO2包覆层的厚度也随之增加,饱和磁化强度Ms在0.86~0.90 T之间变化,Hci基本不变;当添加6 mLTEOS、1 mLAPTES时,得到的包覆粉末包覆效果及性能最佳,饱和磁化强度Ms达到0.90 T,矫顽力Hci为1 114A/m。     

Al2O3微粉添加量对镁合金微弧氧化膜特性影响研究

为了研究添加Al₂O₃微粉对AZ31A镁合金微弧氧化膜特性影响,在不同浓度Al₂O₃微粉电解液中对其进行了微弧氧化处理。利用扫描电镜(SEM)观察微弧氧化膜形貌,能谱仪(EDS)分析了膜层表面Ca、Mg、O、Al元素分布,X射线衍射仪(XRD)分析了相组成,测定了膜厚、硬度和氧化液中Al₂O₃表面电荷,讨论了掺杂改性机理。结果表明,加入Al₂O₃微粉后,氧化电压随Al₂O₃添加量增加先增加后降低;氧化膜表面孔洞数量和尺寸减小,膜层表面Ca元素分布逐渐减少,成膜效率降低,膜层致密度和表面疏松层硬度提高,氧化膜主要由MgO和MgO₄等相组成。     

基于磁过滤技术的热障涂层表面Al2O3 覆盖层抗CMAS腐蚀性能

为了提高热障涂层（TBC）的抗沉积物（主要成分为CaO、MgO、Al₂O₃和SiO₂,简称CMAS）腐蚀性能,采用磁过滤阴极真空电弧（FCVA）技术在TBC表面上制备了致密的Al₂O₃覆盖层,比较和分析了Al₂O₃改性TBC和沉积态TBC的润湿行为和抗CMAS腐蚀性能。结果表明：使用FCVA技术制备Al₂O₃覆盖层的过程对7%（质量分数）氧化钇稳定的氧化锆（7YSZ）相的结构无明显影响,且经Al₂O₃改性的TBC综合性能均优于沉积态TBC。在1250 ℃、CMAS腐蚀条件下,Al₂O₃覆盖层有效地限制了熔融CMAS在TBC表面上的扩散行为。同时,Al₂O₃填充了7YSZ柱状晶之间的间隔并且阻碍了熔融CMAS的渗透,证明了FCVA可作为一种制备Al₂O₃涂层的新方法以提高TBC的抗CMAS腐蚀性能,且Al₂O₃涂层及其制备过程对TBC的热震性能均无消极影响。     

Mo-Al2O3太阳能选择吸收涂层的制备及其光学性能

选用金属Mo作为红外反射层,Mo-Al_2O_3作为吸收层,Al_2O_3作为减反射层,利用磁控溅射镀膜技术,在抛光的316L不锈钢片上制备具有双吸收层的Mo/Mo-Al_2O_3/Al_2O_3太阳能选择吸收膜系,研究减反射层和高、低金属吸收层的厚度及其金属体积分数对膜系选择吸收性能的影响。结果表明,当减反层厚度为50 nm时,所得膜系的选择吸收性能最佳。高金属吸收层厚度的增加会使薄膜反射率的骤升阈值发生红移,薄膜的发射率升高,但其厚度过高,则会影响薄膜的干涉效应。低金属吸收层厚度的增加会导致可见光波段的吸收率增加,红外波段的发射率上升,薄膜反射率的骤升阈值红移。高金属吸收层中金属体积分数增加会导致它的方块电阻降低,使薄膜的红外发射率下降。低金属吸收层中金属体积分数的增加,会导致薄膜的红外干涉下降,使其发射率升高,获得薄膜的最佳吸收率为0.922,发射率为0.029。     

Al2O3-nanodiamond composite coatings with high durability and hydrophobicity prepared by aerosol deposition

We attempted the room-temperature fabrication of Al₂O₃-based nanodiamond (ND) composite coating films on glass substrates by an aerosol deposition (AD) process to improve the anti-scratch and anti-smudge properties of the films. Submicron Al₂O₃ powder capable of fabricating transparent hard coating films was used as a base material for the starting powders, and ND treated by 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) was added to the Al₂O₃ to increase the hydrophobicity and anti-wear properties. The ND powder treated by PFOTES was mixed with the Al₂O₃ powder by ball milling to ratios of 0.01 wt.%, 0.03 wt.%, and 0.05 wt.% ND. The water contact angle (CA) of the Al₂O₃-ND composite coating films was increased as the ND ratio increased, and the maximum water CA among all the films was 110°. In contrast to the water CA, the Al₂O₃-ND composite coating films showed low transmittance values of below 50% at a wavelength of 550 nm due to the strong agglomeration of ND. To prevent the agglomeration of ND, the starting powders were mixed by attrition milling. As a result, Al₂O₃-ND composite coating films were produced that showed high transmittance values of close to 80%, even though the starting powder included 1.0 wt.% ND. In addition, the Al₂O₃-ND composite coating films had a high water CA of 109° and superior anti-wear properties compared to those of glass substrates.     

Y2O3对原位自生TiC增强Ni基涂层组织和性能影响

采用氩弧熔覆的方法,以Ni60A自熔性合金粉末为粘结相,添加Ti粉、C粉和不同含量的稀土氧化物Y₂O₃,在16Mn钢基体上制备出TiC陶瓷颗粒增强金属基熔覆涂层. 运用XRD, SEM等手段对复合涂层的显微组织进行表征和分析,并对熔覆涂层的硬度及耐磨性进行了测试. 结果表明,适量添加Y₂O₃可以使涂层组织中枝晶的方向性减弱、同时细化涂层组织,使涂层组织更加均匀,涂层的硬度和耐磨性有显著提高. 添加2% Y₂O₃熔覆涂层的组织为最细,涂层具有较高的显微硬度和良好的耐磨性能.     

Al2O3纳米粒子环氧涂层对钢筋防护性能的电化学噪声分析

目的研究Al2O3纳米粒子环氧复合涂层对钢筋的防护性能。方法制备Al2O3纳米粒子,将其添加至环氧涂料中,并涂覆在工业钢筋表面成膜。通过XRD和SEM对Al2O3进行表征;利用电化学噪声、交流阻抗谱分析技术,对复合涂层在3.5%(质量分数)NaCl介质中对工业钢筋的防护性能进行测试分析。结果制备的氧化铝纳米粒子的粒径平均为75 nm。通过对电化学噪声测试的有效数据进行时域和频域分析,通过交流阻抗谱分析及数据拟合,认为Al2O3纳米粒子添加量为0.1%(以占环氧树脂质量的百分比计)时,涂层对钢筋的防护性能最好。结论向环氧涂层中添加适量的Al2O3纳米粒子,可以明显提升其对钢筋的防护性能。     

Ti6Al4V钛合金表面Al2O3颗粒改性微弧氧化涂层制备及性能

微弧氧化技术是一门新的表面处理技术,在很多领域有着广泛的应用前景,但其结构受限于电解液成分。本文通过在磷酸盐电解液中加入Al2O3陶瓷颗粒,使得在Ti6Al4V钛合金表面的微弧氧化涂层结构和性能得到改性。涂层的结构和性能通过扫描电镜和XRD衍射仪进行表征和测试,涂层的抗高温氧化性能和热震性能通过高温热循环氧化试验和热震试验进行测试。结果表明,通过在电解液中添加Al2O3陶瓷颗粒,涂层由Al2TiO5 and TiO2组成,涂层更为致密,表现出更为优异的抗高温氧化和热震性能。电解液中游动的Al2O3陶瓷颗粒在微弧氧化过程中被吸入到样品表面并进入涂层,涂层的结构和性能得到改性。     

Characterisation and oxidation of LVOF sprayed Al2O3–40%TiO2 coating on superni 601 and superni 718 superalloys at 800 and 900°C

Failure of components due to high temperature oxidation is the major degradation mechanism in boiler and gas turbine industries. Superalloys having superior mechanical properties and creep resistance are used in these applications but lack resistance to oxidation under aggressive environments. Protective coatings are used to improve their oxidation resistance in such applications. In the present investigation, Al₂O₃–40%TiO₂ coating was deposited on superni 718 and superni 601 superalloys by low velocity oxy fuel process. The as sprayed coating was characterised for microhardness, surface roughness, scanning electron microscopy and X-ray diffraction analysis. High temperature oxidation behaviour of Al₂O₃–40%TiO₂ coated and uncoated superni 718 and superni 601 superalloys has been evaluated at the elevated temperatures of 800 and 900°C for total duration of 50 cycles under cyclic conditions. Each cycle consisted of keeping the samples for 1 h at the elevated temperature followed by 20 min cooling in ambient air. Al₂O₃–40TiO₂ coating in the as sprayed condition showed the presence of Al₂O₃–TiO₂, α-Al₂O₃, TiO₂ as the main phases. Al₂O₃–40%TiO₂ coating on superni 718 and superni 601 superalloys has shown a lower oxidation rate as compared to those of uncoated superalloys. However, the oxidation rate of the coating was not steady due to the occurrence of spallation/sputtering at various stages. The coating was found adherent on the substrate superalloys throughout the study.     

Effect of Feedstock Size and its Distribution on the Properties of Detonation Sprayed Coatings

The detonation spraying is one of the most promising thermal spray variants for depositing wear and corrosion resistant coatings. The ceramic (Al₂O₃), metallic (Ni-20 wt%Cr) , and cermets (WC-12 wt%Co) powders that are commercially available were separated into coarser and finer size ranges with relatively narrow size distribution by employing centrifugal air classifier. The coatings were deposited using detonation spray technique. The effect of particle size and its distribution on the coating properties were examined. The surface roughness and porosity increased with increasing powder particle size for all the coatings consistently. The feedstock size was also found to influence the phase composition of Al₂O₃ and WC-Co coatings; however does not influence the phase composition of Ni-Cr coatings. The associated phase change and %porosity of the coatings imparted considerable variation in the coating hardness, fracture toughness, and wear properties. The fine and narrow size range WC-Co coating exhibited superior wear resistance. The coarse and narrow size distribution Al₂O₃ coating exhibited better performance under abrasion and sliding wear modes however under erosion wear mode the as-received Al₂O₃ coating exhibited better performance. In the case of metallic (Ni-Cr) coatings, the coatings deposited using coarser powder exhibited marginally lower-wear rate under abrasion and sliding wear modes. However, under erosion wear mode, the coating deposited using finer particle size exhibited considerably lower-wear rate.     

反应等离子喷涂 Al2O3-TiB2-Al 复相涂层的反应机理

目的在铝合金表面制备Al2O3-TiB2-Al复合涂层,研究Al,TiO2,B2O3在等离子喷涂中的反应机理。方法采用反应等离子喷涂技术在铝合金表面制备复合涂层,应用扫描电镜与X射线衍射技术测试复合涂层的物相组成和显微组织,并通过燃烧波淬熄试验分析等离子喷涂产物。结果机械球磨可以有效降低粉末发生反应的活化能,等离子喷涂最佳飞行距离范围为150~200 mm。结论喷涂粉末在飞行过程中发生反应,经历了预热、熔化、分解、团聚等过程,验证了最终引燃发生燃烧化学反应的机理。