一种新型的装饰性镀铑工艺

通过耐蚀性人工汗试验、镀层结合力测试、镀层厚度测试以及电镀成本的核算等方法,研究和比较了以钯为基材的镀铑新工艺和以镍为基材的常规镀铑工艺.结果表明:基材和铑镀层的厚度增加时,镀铑产品的耐蚀性会增强,而铑镀层的厚度增加时,耐蚀性增强尤为明显;以钯为基材的镀铑产品外观色泽好、结合力强,较常规工艺有较强的耐蚀性和低廉的镀铑成本,耐蚀时间最高提高了87.5%,在耐蚀性相当的情况下,可节约成本达24%以上.     

探讨KHSO_4熔融法去除金合金铑镀层对火试金结果的影响

铑金属具有很好的化学稳定性,在常温条件下,无机酸、碱和各种化学试剂对其均无作用。金合金首饰镀铑对火试金法检测金含量有一定的影响,本文探讨利用KHSO_4去除金合金表面铑镀层,再用铅火试金法检测金含量受到的影响。     

助镀剂中氯化镍对热浸镀锌层增重、厚度及形貌结构的影响

目前,就热浸镀锌助镀剂中Ni盐含量的变化对镀层的影响研究报道不多。将低碳钢退火板采用不同NiCl2含量的助镀剂助镀后热浸镀锌,并采用扫描电子显微镜(SEM)、光学显微镜(OM)对镀层的厚度、结构、形貌及成分进行分析。结果表明:NiCl2含量在0～6 g/L内,锌镀层质量及厚度随着氯化镍含量的增加而减小,NiCl2含量超过6 g/L时,则不随氯化镍的增加而变化;氯化镍会增加锌镀层中δ金属间化合物相的厚度,细化ζ金属间化合物相,使ζ金属间化合物相更加致密,并减少ζ金属间化合物相的厚度,对η金属间化合物相影响无影响。     

微型空腔化学镀铜工艺研究

介绍了采用有机玻璃(聚甲基丙烯酸甲酯,PMMP)作基底,对施镀表面进行催化活化处理,沉积的铜再产生自身钝化作用而得到一定厚度的铜层制备微型铜空腔的工艺.讨论了化学镀液的主要成分对镀速及镀层质量的影响.结果表明,由此工艺所制备的铜层壁厚范围在10～30μm,长度在2mm左右,镀层铜含量大于95%,为制备惯性约束聚变(ICF)金属腔靶提供了一种新方法.     

Si含量对热浸镀Zn-15% Al层组织的影响

为了解合金浴中Si含量对低Al含量的热浸镀Zn-Al层组织的影响,将Q235钢浸入不同Si含量的Zn-15%Al合金浴中浸镀不同时间,制备了热浸镀Zn-15%Al层。利用扫描电镜、能谱仪等观察镀层形貌结构、分析镀层成分,研究了Si含量对镀层组织的影响。结果表明:Zn-15%Al合金镀层分为Fe-Al界面反应所形成的金属间化合物层和由富Al枝晶和枝晶富Zn相组成的自由层;少量的Si就能强烈地抑制Fe-Al反应,使化合物层减薄,并使自由层晶粒细化;随Si含量的增加,化合物层由Fe2Al5相和FeAl3相向Fe-Al-Si三元化合物4相转变;化合物层厚度随Si含量的增加总体呈减薄趋势,但略有波动;合金浴中含Si时,化合物层主要受扩散控制,其厚度呈抛物线生长规律。     

合金元素锑对热浸镀锌层组织的影响

热浸镀锌中合金元素锑的含量对镀层性能有极大的影响,但对其添加量目前尚无统一标准.对硅含量为0.049%的Q215工业用钢在含0.04%,0.10%,0.30%,0.80%,1.20%Sb的锌池中浸镀0.5～5.0 min获得锌镀层,研究了锌池中添加微量锑对钢铁热镀锌的影响.利用光学显微镜、扫描电镜和能谱仪等测试方法分析了浸镀时间、锌池中锑含量对热浸镀锌合金层组织和厚度的影响.结果表明:添加少量(0.30%以下)的锑对合金层的组织无影响,随浸镀时间延长,镀层厚度呈线性增加;当锌池中添加0.80%Sb以后,合金层组织显著改变,化合物粒子变大,镀层耐蚀性变差;锌池中以锑添加量0.10%～0.30%为佳.     

助镀剂中稀土盐含量对热浸镀锌层组构及性能的影响

以往少见将稀土加入到助镀剂中对热浸镀锌层组构及性能影响的研究报道。为此,在助镀剂中添加混合稀土盐(主要成分为Ce和La)助镀后再热浸镀锌,利用金相显微镜(OM)、扫描电子显微镜(SEM)、电化学测试及全浸腐蚀方法考察了助镀剂中稀土盐含量对热浸镀锌层组织结构及耐蚀性能的影响。结果表明:助镀剂中添加稀土盐能够使镀锌层减薄,有利于改善镀层的微观组织结构,抑制脆性相ζ相的生长,获得由塑性较好的δ相组成的镀层;添加稀土盐有助于改善镀层的耐蚀性能,且耐蚀性能随着稀土盐含量的增加而增强,在稀土盐含量为0.2%时镀层的耐蚀性能最好,之后随着稀土盐含量的增加,镀层的耐蚀性能反而下降。     

钢基表面热浸镀55%Al-Zn-1.6Si合金镀层物相特征及腐蚀行为

采用OM、SEM、EDS、XRD等分析技术研究了镀层锌花特征、成分、相组成及厚度测量;采用辉光放电光谱仪(GDOES)研究沿镀层厚度方向上各元素的含量变化规律;通过盐雾试验对镀层进行腐蚀测试,并探讨镀层在腐蚀过程中的组织演变规律。结果表明:镀层表面锌花呈现树枝叶晶网格状、碎点状、六角星型3种形态,不同形态锌花成分相差无异;镀层整体厚度为17~18μm,外镀层为11~13μm,金属化合物层4~5μm;外镀层相组成除Al、Zn线条外,还有微量的FeAl3相、α-Fe-Al-Si等,且Al、Zn含量之和维持在96%以上;越靠近金属化合物层时,其Al、Zn含量越少,而Fe元素含量逐渐上升,抵达钢基体含量为100%。在中性盐雾试验144h周期内,镀55%Al-Zn-1.6Si合金镀层表现出了优异的耐腐蚀能力。     

铸铁热浸渗铝及其抗高温氧化性能研究

为了研究热浸温度、时间及硅含量对HT200热浸渗铝的影响, 用称重法分析了未镀、浸镀和浸镀加扩散退火处理铸铁的高温抗氧化能力, 用金相显微镜和XRD分析了渗层组织结构.结果表明:镀层厚度随温度升高和时间延长而增大,本试验中浸镀温度740～810 ℃,浸镀时间5～10 min较佳.硅抑制渗层的生长,当镀液硅含量为2%,6%和9%时,镀层厚度分别为384,200 μm和121 μm.渗层结构由外镀层和中间扩散层(以Fe3Al为主)组成,经扩散退火后,渗层主要为Fe2Al5相.浸铝和浸铝且扩散退火处理后的铸铁抗氧化能力提高2～8倍, 耐蚀性显著改善.     

铝锌硅镀层的冲压性能

铝锌硅镀层(Galvalume)作为钢铁基体的热浸镀材料,具有良好的耐腐蚀能力,但是Galvalume镀层在受力变形时容易出现裂纹。针对热浸镀Galvalume镀层成形开裂问题,通过对不同镀层厚度(重量)镀铝锌板进行冲压试验和180°弯曲试验,观察裂纹源的产生。采用扫描电镜(SEM)和能谱(EDS)对镀层及中间过渡层进行研究,分析影响镀层冲压开裂的原因。结果显示:镀层的重量(厚度)是影响其冲压开裂的主要原因,随着镀层厚度的下降,镀层外侧受拉应力作用开裂趋势变小;开裂位置显示主要元素为Fe、Al、Si元素,变形过程中Galvalume合金过渡层相对于镀层更容易开裂;Galvalume合金过渡层的厚度是影响Galvalume冲压开裂的主要原因,随着合金过渡层厚度的降低,过渡层开裂趋势变小。     

疏水改性丙烯酰胺共聚物在水溶液中的缔合

罗丹明B荧光探针发现丙烯酰胺(AM)/丁基苯乙烯(BST)/2-甲基-2-丙烯酰胺基丙磺酸钠(NaAMPS)共聚物(PASA)在0.05 g/dL水溶液中疏水微区的黏度已较大,说明PASA具有强的疏水缔合效应。动态光散射结果表明,PASA在0.005 g/dL极稀溶液中,主要以单分子存在,部分单分子链发生了分子内缔合;在0.01 g/dL~0.2 g/dL范围内,溶液中均有构象伸展和卷曲的单分子存在,粒径有单分子区和疏水缔合区;当共聚物浓度增加为0.3 g/dL时,流体力学半径分布为单分散,只有缔合体存在。随着分子中疏水链段含量的增加,0.1 g/dL PASA溶液的疏水缔合体(Rh:2800 nm~5000 nm)的数量增加,溶液黏度显著升高。     

Mechanism and Kinetics of Rh(IV) Radiation-Chemical Reduction in HNO3 Solutions

Reduction of Rh(IV) in -irradiated and nonirradiated solutions of HNO₃ (0.3-3.0 M) was studied. In both systems, Rh(IV) is completely reduced to Rh(III). The reduction rates in nonirradiated solutions amount to 50-90% of rates in irradiated solutions. Reduction of Rh(IV) with water is postulated. The rates of Rh(IV) reduction in both irradiated and nonirradiated solutions increase with [Rh(IV)] growth and decrease with an increase in [HNO₃] from 0.5-1 to 2-3 M. The dependence of the reduction rates on the dose rate is weak. Mathematical simulation was used to reveal the mechanism and kinetics of radiation-chemical reduction of Rh(IV) in HNO₃ solutions. The rate constant of Rh(IV) reduction with water was calculated by fitting to the experimental data.     

Adsorption and desorption of CO on Ni decorated stepped Rh(553)

Vicinal surfaces are important in surface science, as they show interesting electronic structures and reactivities due to the steps. In this paper the adsorption and desorption of carbon monoxide on the stepped Rh(553) surface decorated with Ni is reported. With 0.1 to 0.3 monolayer Ni on Rh(553) one and two atoms broad Ni wires along the Rh steps are formed. The adsorption and desorption of carbon monoxide on these surfaces is investigated using thermal desorption spectroscopy (TDS) and reflection absorption infra red spectroscopy (RAIRS). TDS shows a marked change from just one broad TDS peak on pure Rh(553) to 4 distinct peaks with increasing Ni decoration. RAIRS shows that already at 0.1 monolayer Ni the CO adsorption states on bridge sites on the Rh step atoms are completely quenched. In addition it is shown that with Ni films up to 3 monolayer the on top adsorption sites for CO on Ni are preferred over the bridge and hollow adsorption sites in contrast to what is known from the Ni(111) surface.     

Adsorption and desorption of CO on Ni decorated stepped Rh(553)

Vicinal surfaces are important in surface science, as they show interesting electronic structures and reactivities due to the steps. In this paper the adsorption and desorption of carbon monoxide on the stepped Rh(553) surface decorated with Ni is reported. With 0.1 to 0.3 monolayer Ni on Rh(553) one and two atoms broad Ni wires along the Rh steps are formed. The adsorption and desorption of carbon monoxide on these surfaces is investigated using thermal desorption spectroscopy (TDS) and reflection absorption infra red spectroscopy (RAIRS). TDS shows a marked change from just one broad TDS peak on pure Rh(553) to 4 distinct peaks with increasing Ni decoration. RAIRS shows that already at 0.1 monolayer Ni the CO adsorption states on bridge sites on the Rh step atoms are completely quenched. In addition it is shown that with Ni films up to 3 monolayer the on top adsorption sites for CO on Ni are preferred over the bridge and hollow adsorption sites in contrast to what is known from the Ni(111) surface.     

Effect of heat treatment of pure and carbon-polluted rhodium samples on the low-temperature resistivity

We present a systematic investigation of conditions for heat treatment of Rh with the aim of increasing the residual resistivity ratio (RRR). The maximal value of RRR for a 25 m thick foil was found to be 1050 and the optimal treatment conditions were high temperatures, above 1400°C, and a low pressure of pure oxygen, around 1 bar. Another batch of foils, containing less magnetic impurities, showed an RRR of only 600. A 0.4 mm thick single crystal was heat treated to an RRR value of 740. Our findings are discussed in the light of a model with magnetic and non-magnetic impurities in Rh, where the latter is found to have an important contribution for this unusual metal. Especially carbon impurities were found to be quite detrimental for the resistivity, and the recovery of the RRR after a carbon contamination is extremely slow in subsequent heat treatments.     

Effect of Zr on microstructure and mechanical property of dispersion-strengthened Pt-20Rh

Dispersion-strengthened Pt-20Rh was designed and prepared by powder metallurgy-internal oxidation-sintering. After rolling and annealing, the microstructures, mechanical properties at room temperature and 1000?°C were tested and analysed. Results indicate that the dispersion-strengthened Pt-20Rh alloy consists of Pt and Rh solid solution, Y₂O₃ and ZrO₂. It has a stabilised grain structure at 1000?°C. As the Zr content increases, the strengths at room temperature and high temperature are greatly improved. ZrO₂ particles can pin up and block the movement of dislocations, making it possible to enhance the strength. When Zr content is 0.3?wt-%, the room temperature and 1000?°C tensile strengths are up to their maximum, i.e. 555 and 149?MPa, respectively.     

Active brain targeting of a fluorescent P-gp substrate using polymeric magnetic nanocarrier system

Magnetic nanoparticles (NP) were developed for the active brain targeting of water-soluble P-glycoprotein (P-gp) substrate rhodamine 123 (Rh123). The NP matrix of poly(lactide-co-glycolide) (PLGA) and methoxy poly(ethyleneglycol)-poly(lactic acid) (M-PEG-PLA) was prepared by single emulsion solvent evaporation of polymers with oleic acid-coated magnetic nanoparticles (OAMNP) and Rh123. All formulations were characterized in terms of morphology, particle size, magnetic content and Rh123 encapsulation efficiency. The maximum encapsulation efficiency of Rh123 was 45?±?3% and of OAMNP was 42?±?4%. The brain targeting and biodistribution study was performed on Sprague Dawley rats (3 groups, n?=?6). Rh123 (0.4?mg?kg(-1)) was administered in saline form, NP containing Rh123, and NP containing Rh123 in the presence of a magnetic field (0.8?T). The fluorimetric analysis of brain homogenates revealed a significant uptake (p?相似文献   

Metal-oxo Cluster Mediated Atomic Rh with High Accessibility for Efficient Hydrogen Evolution

Achieving single-atom catalysts (SACs) with high metal content and outstanding performance as well as robust stability is critically needed for clean and sustainable energy. However, most of the synthesized SACs are undesired on the loading content of the metal due to the anchored metals and the supports as well as the synthesizing methods. Herein, a Rh-SAC with high accessibility by loading it on the metal nodes of metal-porphyrin-based PCN MOFs (PCN-224) as supporting material is reported. Significantly, the PCN-Rh_15.9/KB catalyst with a high Rh content of 15.9 wt% exhibits excellent hydrogen evolution activity with a low overpotential of 25 mV at a current density of 10 mA cm⁻² and a mass activity of 7.7 A mg⁻¹_Rh at overpotential of 150 mV, which is much better than that of the commercial Rh/C. Various characterizations reveal the Rh species is stabilized by the metal nodes bearing −O/OH_x in MOFs, which is of importance for the high loading amount and the good activity. This work establishes an efficient approach to synthesize high content SACs on the nodes of MOFs for wide catalyst design.     

Synthesis, structural and magnetic studies of the CuCr1−xRhxO2 delafossite solid solution with 0 ≤ x ≤ 0.2

The CuCr_1−xRh_xO₂ series is investigated by X-ray diffraction, magnetization measurements and Raman spectroscopy on ceramic samples. It is found that a delafossite solid solution is maintained up to x = 0.2 in CuCr_1−xRh_xO₂. The small observed variation in cell parameters is consistent with the small difference between the ionic radii of Cr³⁺ and Rh³⁺. A significant broadening of X-ray reflections is observed and when analyzed using the Williamson-Hall relationship showed that the strain generated by Rh substitution is strongly anisotropic, affecting mainly (Cr,Rh)-O bonds in the ab plane. Room temperature Raman spectra displayed three main Raman active modes. All modes shift to lower frequency and undergo significant changes in intensity with increasing Rh content, showing the effect of Rh atoms on the M³⁺-O bond strength. The magnetic behavior of CuCr_1−xRh_xO₂ samples was investigated as a function of temperature and applied field. At high temperature paramagnetic behavior, and at low temperature, evidence for weak ferromagnetism, reinforced by a hysteresis loop at 4 K is observed. The magnetic behavior of CuCr_1−xRh_xO₂ is attributed to the disorder of Cr and Rh in octahedral sites resulting in short-range Cr-O-Cr and Cr-O-Rh interactions, which give rise to short-range weak ferromagnetism.     

Luminescent dye-doped KAP nanorods obtained by template assisted crystallization

Luminescent nanorods of potassium acid phthalate (KAP) doped with rhodamine 6G (Rh 6G) dye molecules were grown by template assisted crystallization. Pores with diameters ranging from tens of nanometers to few micrometers were obtained in polycarbonate foils after heavy-ion irradiation and subsequent chemical etching of the damage trails along the ion trajectories. Crystallization from solution was employed for filling of the pores with the dye-doped KAP rods. These nanostructures were characterized using scanning electron microscopy, optical absorption spectroscopy and photoluminescence detection. X-ray diffraction was used for structural analysis. The luminescence of the dye-doped rods undergoes a redshift when the diameter of the structures decreases. This shift is probably caused by increasing dye concentration in the rods with decreasing pore diameter. The luminescence originating from the Rh 6G presence is up-converted due to the second-harmonic generation in KAP.