宽温低浓度镀铬

宽温低浓度镀铬工艺特性是操作温度范围宽(30～50℃)、铬酐浓度低(约传统工艺的1/3),其优点是铬酐消耗少、铬雾和含铬废水污染较少、节约能源、镀液稳定、镀层光亮,适用于镀装钸铬和硬铬。     

电保护络合除锈试验小结

质量,甚至可使成品变为废品,造成很大损失.目前,广泛使用的化学除锈法是采用铬酐、磷酸配方.用铬酐配方的除锈液,优点是黄锈能全部除尽,钢制部份不受影响,保证了轴承等精密仪表的高精密度和高光洁度.然而,长期接触铬酐,对人体健康有严重危害,含铬废液的排放也造成水质污染,这是我们社会主义制度所不容许的.因此,寻找新的可以代替铬酐除锈液的任务就作为一个课题提了出来.我们实验室通过一些小型试验,初步找到了电保护络合除锈的方法.从除锈效率上讲,比目前的铬酐配方既快且好,可以使重锈在短时间内除净;从     

铬酸溶液中铬酐含量和波美度的关系

对铬酸溶液中铬酐含量与波美度关系作连接曲线及拟合曲线图，并将铬酐含量和波美度关系换算成公式，进行相对和绝对误差分析。为了减少误差，对铬酐含量在100－400g/L范围内的铬酸溶液和波美度关系作连接曲线，再进行曲线拟合、公式化。结果表明，得到的公式完全适用于实际生产中通过量波美度来了解镀铬溶液中铬酸含量的换算。     

新型无铬酐电解抛光的研究

研究开发了一种用微量添加剂取代铬酐的新型电解抛光工艺，适用于Ｃｒ１３型马氏体不锈钢工件在真空热处理后的直接电化学光亮处理。通过加入增稠剂和缓蚀剂，降低了电解液的酸含量，抑制了工件表面的局部腐蚀，可得到光亮平整的表面，抛光液寿命长。     

硼酸——化镁快速镀铬工艺

电镀铬一般均沿用铬酐硫酸溶液,这种溶液虽有其独特之处,但电流效率很低,深镀能力较差。我们参考一些国内外有关资料介绍的快速镀铬工艺,进行了试验,采用硼酸、氧化镁作添加剂,使电流效率提高到20～30％,生产效率比一般镀铬提高约两倍,分散能力显著好转。现介绍如下:     

不锈钢表面处理应用技术简介(Ⅱ)

4　不锈钢着色4.1　化学着色奥氏体镍铬钢 1Ｃｒ18Ｎｉ8Ｔｉ可着彩色 ,而铁素体和马氏体不适合着彩色。4 .1.1　工艺流程零件→抛光 (机械抛光、化学抛光和电解抛光 )→清洗→酸洗(10 %硫酸、10 %盐酸、室温时间 5～ 10ｍｉｎ ,只用于机械抛光 )→清洗→着彩色→清洗→固膜→清洗→干燥。4 .1.2　着色铬酐 2 5 0 (2 0 0～ 4 0 0 )ｇ/Ｌ ,硫酸 4 90 (35 0～ 70 0 )ｇ/Ｌ ,温度 70～90℃ ,处理时间不同依次出现蓝色→蓝灰色→黄色→紫色→绿色。影响着色膜的因素有 :(1)材料成分　以 18 8型镍铬奥氏体不锈钢着色最鲜艳 ,其他品种则较差 ;(2 )…     

镀锌层二合一钝化新工艺

1　存在的问题低铬钝化工艺中铬酐含量仅为传统高铬钝化的 2 %左右 ,而所获得的膜层质量与高铬钝化的膜层质量相当 ,其环境效益和经济效益较为突出。就军绿色、橄榄及黑色钝化工艺而言 ,虽然铬酐含量高于低铬钝化 ,但比传统的高铬钝化低得多 ,而且膜层的耐蚀性有明显提高。因此 ,应广泛推广低铬钝化工艺。但是 ,低铬钝化工艺在生产实践中体现诸多优越性的同时 ,也存在不足。(1)酸度问题。如蓝白色钝化 ,虽然铬酐的含量低 ,但其他酸的浓度并不低 (ＨＮＯ3 2 0～ 4 0ｍｌ/Ｌ ,Ｈ2 ＳＯ410～ 15ｍｌ/Ｌ ,ＨＣｌ 5～ 10ｍｌ/Ｌ ,ｐＨ值 0 .5左右…     

锌及锌合金着色技术的研究进展

锌及锌合金的应用量大面广,对其着色处理能大大提高装饰效果和耐蚀性。着色处理的核心工艺是钝化、磷化或染色等技术。综述了锌及锌合金的几种环保型着色技术,如三价铬钝化、无铬钝化、磷化及染色等的研究进展,指出高性能的无铬钝化技术和无铬钝化结合染色技术将是今后研究的重要方向。     

电化学退铜工艺的改进

不良电沉积铜镀层需要退除再重新电镀，经渗碳后的保护铜层也要进行去铜处理，所以，铜镀层的退镀在表面处理工艺中是必不可少的。传统的除铜处理，无论是化学方法，还是电化学方法大多都离不开铬酐，而铬酐是剧毒物质，对环境的污染和人体健康的威胁是不容忽视的。由于铬...     

黄铜制品超低铬钝化处理

为了提高黄铜制品的防腐能力,为表面涂漆打下良好底层,黄铜制品在机械加工以后都将进行表面钝化处理。按传统的钝化工艺,黄铜制品须在铬酐含量高达300g/L的强酸性溶液中进行钝化处理,需要消耗大量的、昂贵的、产生严重污染的铬酐。所以,不但成本很高,而且给废水处理在技术上和经济上造成很大负担。基于这种情况,国内近年来有关单位都在研究和应用无铬或超低铬钝化新工艺,力争消除或减轻环境污染。     

Photostriction of CH3NH3PbBr3 Perovskite Crystals

Organic–inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light–matter interactions. The photoinduced strain of CH₃NH₃PbBr₃ is investigated using high‐resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH₃NH₃PbBr₃ is calculated as 2.08 × 10^?8 m² W^?1 at room temperature under visible light illumination. The significant photostriction of CH₃NH₃PbBr₃ is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation–rotation coupling. Unlike CH₃NH₃PbI₃, it is noted that the photostriction of CH₃NH₃PbBr₃ is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH₃NH₃PbBr₃ for applications in next‐generation optical micro‐electromechanical devices.     

(La2/3Ca1/3)(Mn(3-x)/3)Fex/3)O3体系磁电阻行为的研究

通过系统地测量（La_2/3Ca_1/3）（Mn_{（3-x）／3}Fe_x／3）O₃（x＝0、0.1、0．2、0．3的体系样品的电阻率-温度关系以及一定温度下磁电阻率与磁场的关系,发现随x的变化其磁电阻率峰和电阻率峰均发生位移,磁电阻率峰值增大,并伴生磁电阻率峰展宽效应．作者认为由于Fe的替代,引起体系中Mn³⁺／Mn⁴⁺比率及磁矩的变化,加之外场对磁有序结构的调制作用,从而影响了Mn³⁺－O^－Mn⁴⁺的双交换作用,最终导致磁电阻行为发生变化．     

Constitution of the Ni3Cr-Ni3Al-Ni3W system

Isothermal sections of the Ni-Cr-Al-W system have been investigated at 75 at % Ni and temperatures of 1523 and 1273 K, by means of phase compositional analysis, X-ray diffraction and microscopical examination. The alloys studied lay in the range 2.5 to 10 at % Cr, 12.5 to 20 at% Al, 2.5 to 6.25 at % W, The phases formed were, and the bcc solid solution based on tungsten (designated ₂). The maximum extent of the region was found to be 3 at % each of chromium and tungsten. Preferential partitioning of tungsten to occurred. Study of an Ni-10Cr-12.5Al-2.5W alloy aged at 1273 and 1073 K, after quenching from 1573 K, showed that changes in and compositions and lattice parameters occur as a function of ageing time.     

PbZrO3-CdTiO3 solid solutions

The structural, nonlinear optical, and dielectric properties of (1-x)PbZrO₃ ·xtCdTiO₃ solid solutions were studied. The phase relations in the composition rangesx = 0–0.3 and 0.85-1.0 were established. The results suggest that the ferrielectric ordering in CdTiO₃ persists up to 730 K.     

Phase equilibria in the system LaMnO3 + δ-SrMnO3-LaFeO3-SrFeO3 − d

We have revealed the formation of a continuous series of orthorhombic LaMn_{1 ? y} Fe_yO₃ solid solutions (0<y<1); La_{1 ? x} Sr_xFeO₃ solid solutions in the composition range 0 < x ≤ 0.8, with an orthorhombic structure at 0 < x ≤ 0.6 and a cubic structure at 0.6 < x ≤ 0.8; and a tetragonal SrMn_{1 ? y} Fe_yO₃ phase in the range 0.6 ≤ y ≤ 1. The composition stability limits of the perovskite phase La_{1 ? x} Sr_xMn_{1 ? y} Fe_yO₃ have been determined, and the 1100°C isotherm of the La₂O₃-SrO-Mn₃O₄-Fe₂O₃ system in air has been constructed.     

Multicolor up-conversion emissions of Tm3+/Er3+/Yb3+ tri-doped YF3 phosphors

Tm3+/Er3+/Yb3+ tri-doped yttrium fluoride (YF3) phosphors were prepared by a facile hydrothermal method. X-ray topographic analysis found that the phosphors were crystallized products. Their sizes and morphologies were characterized by scanning electron microscopy (SEM, Hitachi S-4800), which indicated that most of the YF3 phosphors were hundreds of nanometers in size. Up-conversion (UC) spectra were recorded under 980-nm diode laser excitation at room temperature with a fluorescence spectrometer (Hitachi F-4500). Plenty of UC emissions of Tm3+ and Er3+ were observed from ultraviolet to red. For Tm3+ ions, a five-photon process (approximately 291 nm and approximately 347 nm), a four-photon process (approximately 362 nm and approximately 452 nm), and a three-photon process (approximately 475 nm) were identified in the UC spectra. The UC emissions from the Er3+ were: approximately 380 nm, approximately 408 nm, approximately 521 nm, approximately 537 nm, and approximately 652 nm. Therefore, cyan-white light can be observed by the naked eye at 980-nm excitation, even under low excitation power density. By comparing the UC spectra of the phosphors annealed at different temperatures, we found that the intensity of the UC luminescence increased as annealing temperature increased. Furthermore, the spectral dependencies on Tm3+ doped concentrations were studied. The energy transfer processes and fluorescence dynamics in the tri-doped system are currently being investigated.     

3 Cr3 Mo3 VNb 在热冲孔中的应用研究

高合金钢热冲孔冲头寿命关系到模具与产品成本、生产效率、自动化设备的使用,因此,应注重冲头的选材、材料制备与冲头制造工艺。 用 3 Cr3Mo3 VNb 作为高合金钢热冲孔冲头,为提高模具寿命,在材料制备上,优化了成分,采用电渣重熔冶炼,减少杂质,毛坯锻造两次,用大锻造比锻造,冲头热处理用真空炉,三次回火,热处理硬度取 HRC42 ~ 46 ,冲头表面处理采用镀铬工艺,开展了热冲孔工艺试验。 结果表明,用3 Cr3Mo3 VNb 可使冲孔冲头寿命平均达到 800 件以上。     

Processing and properties of Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramic relaxors

The shrinkage phenomenon during the reaction-sintering of PMN-PZT from low-temperature pre-reacted 3PbO + MgNb₂O₆ + PZT powder mixtures has been studied. It was assumed that the pre-reaction treatment leads to the formation of a pyrochlore phase containing very active MgO small particles, and that the strong shrinkage occurring up to 800 °C took place by the diffusion of Mg²⁺ cations into the pyrochlore phase particles, thus controlling the reaction-sintering shrinkage phenomenon. Above that temperature the densification was enhanced by a liquid-phase sintering process. The ceramics sintered at 1050 °C for 2 h showed 96% of the theoretical density, and the dielectric constant of such a sintered ceramic showed a maximum value of 17 000 at 1 kHz. It was also found that the dielectric constant decreased with increasing grain size. Although the role of PZT in enhancing the dielectric constant of otherwise low-purity PMN ceramics is not clear, the increase in K is assumed to be a solid-solution effect. The presence of impurities and the PbO stoichiometry could be influencing the not too high dielectric constant value of PMN-PZT ceramics.