不锈钢环保型彩色工艺及其耐腐蚀性能

通过对传统着色工艺的改进,摸索出了一种以硫酸亚铁铵为主盐的低温、无铬、环保的配方,添加适量的添加剂,利用微机控制着色时间,得到了蓝色、黄色、紫红色、绿色和褐色五种色彩。采用扫描探针和X射线光电子能谱等表面分析手段,研究了着色膜的表面形貌和元素组成,并采用动电位扫描的电化学方法考察了着色膜的耐腐蚀性能。结果表明,着色膜主要由铁、氧等元素组成,着色膜色泽鲜艳、光亮。着色后的不锈钢耐蚀性优于未着色的试样,随着色膜厚度的增加耐蚀性增强,此工艺操作温度低(50~60℃),具有较高的应用推广价值。     

碱性介质中304不锈钢交流调制电位着色工艺研究

为了改善不锈钢着色过程中高温和重离子的环保和耗能问题,室温下,在无Cr的NaOH溶液中304不锈钢交流调制电位法着色处理工艺,该工艺具有经济环保的特点.获得了稳定的金黄色、黄紫色、紫色、蓝紫色和蓝色膜,着色膜具有良好的耐蚀性,耐磨性、机械加工性和抗污性.探讨了工艺参数对着色膜耐蚀性和稳定性的影响.结果表明:着色电压幅值为7.0～8.0V、着色时间为4～7min时,着色膜稳定性和耐蚀性能最好.     

口腔医用不锈钢托槽表面着色及膜层成分研究

为了获得重现良好﹑色彩鲜艳的不锈钢表面色彩和了解不锈钢表面着色膜的成分,采用了电位控制不锈钢表面着色方法;并利用俄歇能谱分析表面膜层成分.研究表明通过利用电位变化曲线能够控制不锈钢表面氧化膜的厚度,使着色工艺易于控制,同时分析了化学着色溶液的温度和浓度﹑着色时间对不锈钢托槽表面颜色的影响,测定了着色过程中的电位变化曲线.俄歇能谱成分分析表明不锈钢表面膜层含有Cr、Fe、S、O等元素.     

不锈钢着色的光干涉效应

采用化学氧化法,测定不锈钢在着色溶液中,着色电位与颜色的对应关系,并采用俄歇能谱测定了着色膜的化学元素组成和膜厚与着色电位的关系.根据薄膜光干涉原理,提出了颜色与膜层的关系式,对着色膜层的折射率进行了估算.     

科技简讯

锡-铜盐电解着茶色铝阳极氧化膜电解着色工艺,具有色膜耐磨、耐晒、耐腐蚀、耐高温、生产成本低、效率高等优点,所以在家用电器、日用五金、建筑材料等铝制品中得到广泛应用。锡-铜盐着茶色的工艺配方是:硫酸亚锡3-5克/升,硫酸铜5-10克/升,HEDP40-50毫升/升,工作电压10-15伏,温度10-40℃,时间45-60秒。着色随时间的变化规律:青铜色→浅茶色→     

常规脉冲伏安法制备黑色不锈钢及性能测试

通过试验研究,提出了一种新型的不锈钢着色工艺--常规脉冲伏安法着黑色,即在无铬的硼酸缓冲液中,通过加入添加剂(自配)降低着色温度,进行电化学着色.测试了着色样品在3.5%NaCl溶液中的耐蚀性.采用扫描探针显微镜(SPM)观测了着色膜封膜前后的形貌.结果表明,常规脉冲伏安法着色工艺是一种低温、无铬的不锈钢着色的新型环保工艺,所得到的不锈钢着色膜光亮美观、呈黑色,同时具有优良的耐磨性和耐热性.     

铝表面的交流电解着色工艺

1 引言铝是一种很活泼的金属,其还原电位是—1.67V(A1~(3+)+3e(?)A1).它很容易与空气中的氧气发生化学反应,生成一层则A1_2O_3膜.这种自然生成的氧化膜极薄(仅1.0～5.0×10~(-8)m).呈非晶形多孔状,厚度很不均匀,故不能有效防止铝表面继续被腐蚀,且氧化膜上的微孔易吸附空气中的灰尘、污物.我们常见的那种未经处理的本色铝制卷闸门,使用半年后表面发暗、出现腐蚀斑点就是例证.解决的办法是对铝制品表面进行化学(包括电化学)处理.2 铝表面交流电解着色工艺流程近20年来,国际上流行的是“二步法”交流电解着色工艺.这里提供的“二步法”交流电解着色工艺生产流程是:表面除油→清洗→化学抛光→两级清洗→阳极氧化→清洗→交流电解着色→清洗→封闭处理→清     

黄铜化学着色工艺

为了在黄铜基材上室温下获得铁锈色、棕色、枪黑色、仿古绿色膜层,研究了黄铜酸性化学着色工艺.主要讨论前处理、溶液组分、pH值和着色时间等因素对着色膜层质量的影响,并提出工艺维护的措施.研究结果表明:溶液组分是影响化学着色膜颜色的主要因素,使用时要注意控制其含量;适量的添加剂可以提高色膜质量;总之,只有掌握合理的着色工艺参数,才可以得到满意的着色效果.     

黄铜化学着色膜层制备及表征

采用3种黄铜表面化学着色工艺,分别在黄铜表面得到了黑色、红色和银白色膜层。用SEM观察了膜层的表面形貌,用EDS对膜层进行了成分分析,用XRD对膜层进行了物相分析,并测试了着色黄铜的耐蚀性和结合力性能。实验结果表明,3种着色黄铜的耐蚀性较好,且着色膜层与基体结合良好。     

厨具用不锈钢的表面化学着色

研究了一种厨具用不锈钢的表面化学着色工艺.探讨了硫酸锌用量、温度、时间和封闭方法对着色膜性能的影响,得出了最佳工艺参数.结果表明:该工艺操作温度范围宽,维护简单,具有推广价值.所得的着色膜色泽鲜艳,均匀,耐蚀性、耐磨性、耐热性、耐油污性好,能满足厨具的要求.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.