PMMA/硅铝包覆铝酸锶复合发光材料的制备和发光性能

采用原位乳液聚合法制备了聚甲基丙烯酸甲酯(PMMA)/硅铝包覆(SrAl2O4:Eu,Dy)复合发光材料。通过傅立叶变换红外光谱(FT-IR)和热失重(TGA)测定,研究了复合发光材料的结构,结果表明,复合发光材料中聚合物分子与硅铝包覆(SrAl2O4:Eu,Dy)之间是通过键合的方式结合;通过荧光光谱和发光亮度测试,研究了复合发光材料的发光特性和余辉性能,结果表明,在硅铝包覆(SrAl2O4:Eu,Dy)表面共价结合上PMMA后仍能保持SrAl2O4:Eu,Dy原有的发光性能。     

磷光粉表面包覆对铜基磷光复合材料发光及摩擦性能影响

选用热稳定性好的SiO2为包覆物,采用溶胶-凝胶法,以正硅酸乙酯为硅源,对商用磷光粉SrAl2O4∶Eu2+,Dy3+表面进行包覆,以解决磷光粉在高温下制备复合材料过程中因与金属粒子接触以及高温氧化产生猝灭的问题。实验通过热压烧结制备块体铜基磷光复合材料,考评包覆工艺对高温下制备的复合材料发光及摩擦性能的影响。通过X射线衍射、扫描电镜、荧光分光仪等设备对包覆前后磷光粉的表面形貌和发光性能进行分析和表征,采用摩擦试验机对包覆前后磷光粉与高铝青铜粉末混合制备复合材料烧结试样的摩擦性能进行研究。结果表明磷光粉表面包覆可有效避免其在高温下氧化猝灭和接触猝灭,包覆后磷光粉应用于铜基复合材料中可有效降低复合材料的磨损量,提高材料的耐磨性,当包覆比为10%时复合材料的发光性能、耐磨损性能最佳。     

碱土铝酸盐长余辉发光颜料表面包膜的研究

采用四乙氧基硅(TEOS)为硅包膜剂,在SrAl₂O₄:Eu²⁺,Dy³⁺发光颜料颗粒表面进行包膜,通过扫描电镜(SEM)、粒度测量、BET比表面积测试及X射线光电子能谱(XPS)分析,证实发光颜料颗粒表面包覆了一层厚度约为14nm的致密均匀的SiO₂纳米膜.耐水性能及发光性能测试表明,包膜后发光颜料耐水性明显改善,发光性能变化较小.分析表明包膜过程实际上是水合二氧化硅在颜料颗粒表面的溶胶-凝胶过程,其最佳工艺条件为:包膜溶液pH约为10;包膜温度控制在80℃;包膜时间为3.0h.     

TiO2负载硅铝陶瓷介孔球对甲基橙吸附和光催化 降解的研究

：以自制硅铝陶瓷介孔球为基体,经溶胶凝胶法制备TiO2溶胶并将其负载于硅铝陶瓷介孔球表面,用于甲基橙溶液的吸附和光催化降解,再利用扫描电子显微镜、X射线衍射仪、傅里叶变换红外光谱仪和可见分光光度计对样品的表观形貌、晶体结构、吸附和光催化性能等进行表征和测定。研究结果表明：TiO2是以粗糙度较高的多层膜包覆于硅铝陶瓷介孔球表面且TiO2为锐钛矿晶型;在黑暗条件下,硅铝陶瓷介孔球和TiO2负载硅铝陶瓷介孔球对甲基橙仅起到吸附作用,且两者的吸附性能较接近;但在紫外光照条件下,TiO2负载硅铝陶瓷介孔球对甲基橙除有吸附作用外还表现出较好的光催化降解活性。     

耐水型SrAl2O4∶(Eu2+,Dy3+)发光材料制备及性能测试

采用硅烷偶联剂对SrAl₂O₄∶(Eu²⁺,Dy³⁺)发光材料进行耐水性表面包覆,比较不同包覆材料及用量下包覆效果的差异,并通过耐水性实验、余辉性能实验、超景深显微镜、扫描电镜、X射线衍射仪等手段对包覆前后的发光材料进行微观观察及表征,研究改性前后材料性能、表面形貌与成分的差异。结果表明,当以KH560为偶联剂、包覆比为9%(wt,质量分数)时,硅烷偶联剂能均匀地包覆在长余辉发光粉表面,可有效提高材料的耐水性能,同时发光材料的发光性能未受影响。     

8-羟基喹啉铝表面包覆SiO2的研究

以有机电致发光材料-8-羟基喹啉铝(Alq3)为研究对象,在其表面包覆SiO2来改善有机电致发光器件中的材料界面,从而延长器件寿命.利用透射电子显微镜、光致发光光谱、热重分析分别对产物的形貌、发光性能和热稳定性进行了表征,借助扫描电镜和X射线光电子能谱仪对产物的薄膜进行了微观分析,分别以Alq3和包覆了SiO2的Alq...     

水性苯丙乳液长余辉蓄能发光涂料的制备与性能

为了提高新型碱土铝酸盐掺杂稀土元素发光材料的耐水性能,并保持其良好发光性能,以硅酸钠为硅源,采用液相沉积法在SrAl2O4:Eu2+,Dy3+长余辉荧光粉表面包覆SiO2膜。通过红外光谱(IR)、扫描电镜(SEM)、酸度计考察了包覆效果,优选了包覆反应条件。以包膜发光粉为颜料,水性苯丙乳液为成膜物质,添加适量的助剂,配制了一种水性蓄能发光涂料。用激发和发射光谱、发光亮度及余辉衰减研究了涂料及其涂膜的发光特性,优选了发光粉用量,并对发光涂料及其涂膜的其他性能进行了测试。结果表明:当SiO2包覆量为9%(质量分数),反应温度为80℃时,SiO2能均匀地包覆在SrAl2O4:Eu2+,Dy3+长余辉荧光粉表面,使其耐水性提高,而又不影响其发光性能;日光和一般的荧光灯都可以有效激发该发光涂料,当发光粉含量为20%(质量分数)时,水性蓄能发光涂料及其涂膜的综合性能优良,余辉时间可达12 h以上。     

用于水性涂料的铝银浆研究

研究了铝粉表面包覆的机理。通过硅烷偶联剂、丙烯酸树脂、酒精等成功地在铝粉表面包覆一层含硅聚合物膜,实验表明,在水性助剂的包覆下,用水作溶剂成功地制备了用于水性涂料的铝浆。     

掺入纳米级含硅微粒的复合铝氧化膜耐蚀特性研究

采用电化学途径,通过铝合金在一次电解、二次电解过程中,掺入纳米级的含硅微粒,制备掺硅复合铝氧化膜.借助于先进的结构和性能表征手段,探讨了掺硅复合铝氧化膜的结构、组成及耐蚀机理.对膜层进行了盐雾、霉菌、高温、低温、交变湿热和南海服役环境下的自然暴晒试验.结果表明,该膜层具有优良防护性能.     

Al@SiO2@Al2O3双层复合材料的可控合成及其耐腐蚀与力学性能

为了有效提高铝颜料的耐腐蚀与力学性能,通过一种温和有效的Sol-Gel法,首先在铝颜料表面包覆一层SiO2,再通过异丙醇铝水解产生A12O3,从而制备了 Al@ SiO2@ Al2O3的双层复合材料。利用扫描电镜、EDS谱、红外光谱、X射线衍射等分析手段对包覆前后的铝颜料的微观形貌及包覆层成分进行分析和表征;通过析氢试验来考察样品的耐腐蚀性能;并将双层包覆的铝颜料添加到PVC树脂中,研究铝颜料对PVC树脂的拉伸性能和硬度的影响。结果表明:表面包覆质量分数约10%的SiO2和4%的A12O3,室温条件下,反应时间为4 h,Al2O3能够在铝颜料表面形成表面光滑、致密的包覆层,在浓度为0.5 mol/L的盐酸中,缓蚀效率达84.6%;添加0.10%(质量分数,下同)铝颜料,PVC树脂的拉伸强度提高45.77%,断裂伸长率提高46.55%,硬度提高27.05%;添加0.15%铝颜料时PVC树脂的光泽度有89.7Gs.     

Effect of grinding on plain fatigue and fretting fatigue behaviour of detonation gun sprayed Cu–Ni–In coating on Al–Mg–Si alloy

Uniaxial plain fatigue and fretting fatigue tests were carried out on detonation gun sprayed Cu–Ni–In coating on Al–Mg–Si alloy samples. The samples in three conditions were considered: uncoated, as-coated and ground after coating. Ground coated specimens exhibited superior plain fatigue and fretting fatigue lives compared with uncoated and as-coated specimens. The life enhancement has been discussed in terms of surface finish and residual compressive stresses at the surface.     

Thermo-mechanical behavior of the Al–Si alloy coated hot stamping boron steel

Hot tensile tests of boron steels with and without an Al–Si coating were performed using a Gleeble 3500 test system, at temperatures of 700–850 °C and strain rates of 0.01–1/s. The phase and microstructure of the coating in as-coated and press-hardened conditions were observed under scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis and X-ray diffraction (XRD). Experimental results indicate that the Al–Si coating gave an unignorable influence on the thermo-mechanical properties of the boron steels. The ultimate tensile strength (UTS) of the Al–Si coated boron steel was almost equal to that of the uncoated under the lower strain rate at the same deformation temperature. At a higher strain rate, the UTS value appeared to be lower than that of the uncoated. Moreover, the UTS difference increased with the decreasing deformation temperature. The ductility of the Al–Si coated steel was lower than that of the uncoated under the described test conditions. Following the tensile tests, extensive cracks were visible in the Al–Si coating layer. SEM observation showed that microcracks and voids appeared after austenization, which may act as nucleation sites for the cracks. The cracks first propagated in the direction perpendicular to the coating/substrate interface and were identified as Type I cracks. The propagation was hindered by the substrate when these cracks reached the coating/substrate interface. This occurred because the interfacial bonding strength between the coating and the substrate was lower than the substrate strength. Following this initial failure, the cracks turned to propagate paralleled to the coating/substrate interface. In addition with the shear stress resulting from the substrate yielding, Type II cracks formed. Eventually, the cracked coatings were accompanied by interface decohesion from the substrate. The width and density of the cracks were found to increase with the decreasing deformation temperature and rising stain rate.     

超音气体雾化Al-Si合金粉末表面氧化和吸附特性

利用超音速气体雾化法制备Al-17Si-6Fe-4.5Cu-0.5Mg合金粉末，借助X射线光电子能谱（XPS）对粉要态合金表面氧化和吸附特性进行了研究，并对粉末表面层结构进行了分析。结果表明：粉末表面氧化主要以Al和Mg元素的氧化为主，氧化层成分主要为Al2O3，Al(OH)3和MgO，而合金中的Si,Fe及Cu元素很少氧化。除此之外，在粉末表面化还吸附一层含Cl元素的碳氢有机化合物污染层，测定表明粉末表面氧化层和吸附层总厚度约为2nm。     

Effect of copper electroless coatings on the interaction between a molten Al–Si–Mg alloy and coated short carbon fibres

The role of electroless copper coatings applied on short carbon fibres on the interaction between an aluminium alloy (Al–Si–Mg) and coated fibres has been studied to get useful information for the fabrication of carbon fibre reinforced aluminium matrix composites by liquid or semi-liquid processing. The conditions used for electroless were optimized to obtain a uniform and continuous layer of copper. After characterization, uncoated and Cu coated carbon fibres were mixed with AA 6061 aluminium powders, compacted and heated at temperatures from 650 to 950 °C to study the reactivity and the resulting interface. To complete this study, differential thermal analysis (DTA) were carried out on compacted mixtures of aluminium alloy powders with Cu coated and uncoated carbon fibres, applying similar thermal cycles than for the composite manufacturing. The results show an important improving of reinforcement wetting by molten matrix when copper coatings are applied, jointly with a reduction of the alloying elements microsegregation in the matrix, unlike the composites manufactured with uncoated fibres. Additional microhardness and nanoindentation tests were carried out to study the effect of the copper incorporation from the coating to the matrix on the matrix response to the ageing hardening.     

Magnetic properties of magnetite nanoparticles coated with mesoporous silica by sonochemical method

In this paper we present the magnetic properties of mesoporous silica-coated Fe₃O₄ nanoparticles. The coating of magnetite nanoparticles with mesoporous silica shell was performed under ultrasonic irradiation. The obtained mesoporous silica-coated magnetite nanoparticles were characterized by powder X-ray diffraction, focused ion beam-scanning electron microscopy, nitrogen adsorption-desorption isotherms and vibrating sample magnetometer. The hysteretic behavior was studied using first-order reversal curves diagrams. The X-ray diffraction result indicates that the extreme chemical and physical conditions created by acoustic cavitations have an insignificant effect on crystallographic structural characteristic of magnetite nanoparticles. Changes in the coercivity distributions of the magnetite nanoparticles were observed on the first-order reversal curves diagrams for the samples with coated particles compared with the samples containing uncoated particles of magnetite. The coated particles show an increased most probable coercivity of about 20% compared with the uncoated particles which can be associated with an increased anisotropy due to coating even if the interaction field distribution measured on the diagrams are virtually identical for coated/uncoated samples.     

包覆和凝胶注模成型对氮化硅陶瓷性能的影响

利用含 Al (NO3) 3,Y (NO3) 3和尿素的水溶液中无机盐的沉淀再经煅烧在 Si3N4粉料的表面包覆 Y2 O3- Al2 O3层 ,作为氮化硅烧结的助烧剂。包覆层改变了 Si3N4粉料的电动性和胶态特性 ,从而提高了 Si3N4的分散性。研究表明 ,经包覆和凝胶注模成型的方法所制备的氮化硅烧结体较冷等静压方法所获得的烧结体的抗弯强度和 Weibull模数都大大提高     

Effect of tungsten coating on the relaxation time of photoconductivity in annealed Czochralski-Grown Si

The effect of tungsten coating on the degradation of the relaxation time of photoconductivity in Czochralski Si upon annealing was studied. It was found that the concentration of process-induced defects in tungsten-coated Si annealed at 800 and 900°C exceeded that in uncoated samples. Moreover, the annealed tungsten-coated samples showed stronger temperature dependences of the electron capture cross section of these defects, which suggests that the defects produced in these samples differ from those in uncoated Si. No additional recombination channels were found in the tungsten-coated sample annealed at 1000°C as compared to the uncoated samples. The resistivity and conductivity type of tungsten-coated Si remained unchanged upon annealing.     

High temperature stability of multicomponent TiAlSiN and CrAlSiN coatings

The high temperature oxidation behavior of TiAlSiN and CrAlSiN coatings was studied. These coatings were deposited on silicon substrates by using a cathodic-arc deposition system with lateral rotating arc cathodes. Titanium, chromium and Al88Si12 cathodes were used for the deposition of TiAlSiN and CrAlSiN coatings. All the deposited Ti(0.49)Al(0.44)Si(0.07)N, Ti(0.41)Al(0.51)Si(0.08)N and Cr(0.50)Al(0.440Si(0.06)N coatings showed B1-NaCl crystal structure and possessed nano-grain sizes of 6-8 nm. For the high temperature oxidation test, the coated samples were annealed at 900 degrees C in air for 2 hours. The Ti(0.41)Al(0.51)Si(0.08)N with higher Al and Si contents possessed lower oxidation rate than that of Ti(0.49)Al(0.44)Si(0.07)N. The oxide layer formed on the Ti(0.49)Al(0.44)Si(0.07)N coatings consisted of large TiO2 and TiAlSiN grains at the oxide-coating interface, followed by a layer of Al2O3 in the near-surface region. The oxidation rate of the Cr(0.50)Al(0.44)Si(0.06)N coated sample was much lower than that of the Ti(0.49)Al(0.44)Si(0.07)N and Ti(0.41)Al(0.51)Si(0.08)N. The dense Al2O3 with amorphous top layer at the oxide-coating interface retarded the diffusion of oxygen into the Cr(0.50)Al(0.44)Si(0.06)N. The deposited Cr(0.50)Al(0.44)Si(0.06)N showed a high temperature performance superior to those of the Ti(0.49)Al(0.44)Si(0.07)N and Ti(0.41)Al(0.51)Si(0.08)N.