渗铝不锈钢钢管酸洗钝化液及其工艺研究

以硝酸、氢氟酸、硫酸、盐酸、缓蚀剂、添加剂作为调整对象,进行正交优化试验,通过目视法评定酸洗钝化质量,优化酸洗钝化液的合适配比,并且研究在不同酸洗钝化时间下不锈钢钢管渗铝涂层的厚度变化情况。结果表明:含有硝酸10%、氢氟酸5%、盐酸5%、硫酸5%、缓蚀剂0.75%、添加剂0.5%的酸洗钝化液酸洗钝化效果良好;酸洗钝化2 min就能在快速有效地去除氧化皮的同时保持渗层的完整性;酸洗钝化30 min后涂层剩余厚度仍大于20μm且渗铝涂层均匀、致密,不锈钢钢管表面色泽明丽、平整光滑。     

超导材料用铌表面清洗工艺

采用乳化剂溶液在超声波作用下对金属铌表面进行去油去灰清洗,并用硝酸和氢氟酸混合酸液进行酸洗,通过扫描电镜(SEM)、光电子能谱(XPS)及腐蚀深度对清洗表面进行分析。结果表明:采用乳化剂溶液在超声波作用下清洗对去油去灰有很好效果,可以获得均一的酸洗初始腐蚀界面,其中乳化剂温度为40～50℃,超声波频率为20～25kHz,采用混合酸液浓度为35%分析纯硝酸和10%分析纯氢氟酸的清洗工艺能达到较好的清洗效果和均一的表面状态。合理控制硝酸和氢氟酸浓度对于保证清洗质量和防止材料吸氢脆化很关键,通过腐蚀可以实现表面以Nb2O5状态存在转变为以单质铌存在,实现氧化物的溶解,改善表面结构;铌清洗后在环境放置稳定性强,不容易吸水、氧化和变质;清洗液特征可以通过游离氟离子、铌离子、酸度进行表征。     

黄铜制品清洗新法

黄铜清洗,常采用铬酸钝化法,但排出的废液,对生物和人体都有危害.近年国内研制了一些新钝化法,如硫酸氧钛法、磷酸铬酸盐电解抛光法以及双氧水苯三唑法等,但对黄铜均不理想.上海液压气动技术研究所采用混合酸(磷酸、硝酸、醋酸等)进行去毛刺酸洗;效果较佳,以     

不锈钢容器的膏剂法酸洗钝化

酸洗钝化处理是增强不锈钢防腐蚀性能的常用方法,本文结合我公司不锈钢容器酸洗钝化处理的施工情况,介绍了容器膏剂法酸洗钝化的工艺流程,并结合生产实际对膏剂法酸洗钝化中存在的问题进行了分析,提出了自己的改进观点。     

马氏体不锈钢酸洗溶液测定方法

对马氏体不锈钢酸洗溶液成分测定的化学分析方法进行了研究。结果表明：酚酞可以做马氏体不锈钢酸洗槽液中氢氟酸、硝酸的总量指示剂,用氢氧化钠标准溶液滴定得到。对于其中的氢氟酸,pH值在2.9~3.4范围内,以茜素磺酸钠做指示剂,用硝酸钍标准溶液滴定溶液中的氟离子。氢氟酸、硝酸的总量与氢氟酸含量之差即为硝酸的含量。氢氟酸测定的回收率在100.3%~101.9%之间,相对标准偏差为0.004%。硝酸测定的回收率在99.1%~101.3%之间,相对标准偏差为0.01%,实现了对马氏体不锈钢酸洗溶液的质量控制。     

钛及其合金酸洗废液回收研究

通过实验研究论证了以ＳＦ－１１为沉淀剂再生酸洗液的可行性,试验了ＳＦ－１１加入量对酸液再生效果的影响,再生酸中补加氢氟酸和硝酸量对酸洗效果的影响。选择了酸洗液再生循环和酸洗的最佳条件,实验证明,再生酸的酸洗速度和酸洗件质量完全满足生产要求,有较高的社会效益和经济效益。     

热镀锌层钛盐钝化膜耐蚀性能的研究

以钛盐为主盐,加入双氧水、硝酸(磷酸)、络合剂等配制无铬钝化液,经钝化后在镀锌层表面获得一层均匀的无铬钝化膜.通过电化学试验、盐雾腐蚀试验、大气暴露试验等测试手段对比研究了铬酸盐钝化膜、钛盐钝化膜、镀锌层的耐蚀性能以及影响钝化膜耐蚀性的因素.结果表明:镀锌层经钛盐钝化后耐蚀性能明显改善,在中性盐雾箱内可以通过48 h连续喷雾而不产生白锈.     

车用高强钢酸洗数学模型的研究

目的研究酸液浓度、温度和氧化皮厚度对车用高强钢酸洗时间的影响,建立关于酸液浓度、温度和氧化皮厚度的综合酸洗模型。方法引入电位导数近零法判断酸洗结束时间,通过进一步酸洗实验研究酸液温度、浓度变化对不同厚度氧化皮酸洗时间的影响,对实验数据进行多元拟合,最后利用正交试验对三种影响因素进行相关性分析。结果当酸洗液电位导数值达到-0.0025 V/s时,氧化皮已去除干净;当酸液浓度提升到10%时,酸洗时间大大减少,而继续提高酸液浓度对缩短酸洗时间的帮助不大。酸液温度在达到80℃时,酸洗效率值达到最高,再提高温度,不仅浪费能源,而且会增加盐酸挥发,反而可能延长酸洗时间。建立了综合酸洗模型并将实际高强钢酸洗数据带入检验,发现酸洗时间误差在8%以内。氧化皮厚度对酸洗时间的影响超过酸液温度和浓度。结论带钢酸洗有适宜的酸液浓度和温度,不能一味地通过增加酸液浓度和温度来提高酸洗效率。通过正交实验发现,建立包含氧化皮厚度影响因素在内的综合酸洗控制模型,对预测酸洗结束时间有较好的准确性和有效性,在工程上具有重要意义。     

硝酸镧含量对锌铝涂层组织结构和耐蚀性的影响

以稀土硝酸镧为添加剂,用硅烷钝化液代替铬酐,通过添加不量的硝酸镧制备了水性无铬锌铝涂层。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱(EDS)分析、中性盐雾试验和极化曲线等对含硝酸镧涂层试样的结构和性能进行了评价。结果表明：含5 g/L硝酸镧(指其在B组分中的质量浓度)涂层试样的耐蚀性最好,适量的镧盐可以改善涂层结构,使涂层均匀致密;硝酸镧钝化处理可以显著降低涂层试样的腐蚀电流,提高腐蚀电位,抑制腐蚀速率,提高涂层的耐蚀性。硝酸镧也可以作为物理屏障,阻止腐蚀介质渗透到涂层中,但它不改变极化曲线的形状。水性无铬锌铝涂层中硝酸镧的最佳用量为5 g/L。     

某发射装置液压导管酸洗问题分析与改进

某发射装置液压系统不锈钢导管酸洗后出现了接头锈蚀、密封面颗粒状过腐蚀等问题。针对上述问题,从接头材质、酸液配比、酸洗工艺等方面进行分析,提出减少酸洗时间、降低酸液酸度等改进方案。经试验、使用验证表明:改进后的方案能够满足酸洗要求,解决了接头锈蚀、密封面颗粒状过腐蚀等问题。     

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.