钢基热浸镀锌的研究

简要介绍了热浸镀锌的工艺，分析了热浸镀锌时镀层的形成以及浸镀温度对镀层厚度的影响，分析了锌池合金元素对热浸镀锌的影响及硅的反应性问题。     

热浸镀锌浴中的Ni,Sb对合金镀层组织的影响

Ni,Sb对热浸镀锌层组织及性能有较大影响,但两者的共同作用对热浸镀锌合金层组织的影响尚不清楚。为了在获得美丽锌花的同时获得合适厚度的热浸镀锌合金层,配制了11种锌浴对Q235钢热浸镀锌。采用光学显微镜、扫描电镜和能谱仪等测试方法研究了锌浴中Ni,Sb的共同作用对热浸镀锌合金层组织和厚度的影响。结果表明:单独向锌浴中添加Sb不能有效降低Q235钢热浸镀锌合金层的厚度,同时加入Ni和Sb,两者共同作用可以减缓热浸镀锌过程中的Fe-Zn反应速度,降低镀层厚度;同时添加0.05%Sb和0.4%Ni可获得理想厚度的镀层。     

超厚热浸镀锌工艺的探讨

由于热浸镀锌的工艺简单易行,保护性能及其它综合技术-经济指标显著优于喷镀锌、电镀锌、富锌漆以及粉镀锌层(Sher-adizing)而广泛用于钢铁的表面保护. 热浸镀锌层的厚度将直接影响到镀件在使用条件下,特别是在恶劣苛刻的环境条件下的使用寿命.而目前国内的热浸镀锌工艺一般仅能达到相当于ASTM A级的水平.如何改进热浸镀工艺条件,增加钢铁表面的载锌量,达到B级,进而达到C级的水平,以适应国际市场上大量的订货需求,这是我国热浸镀锌工业中一个十分重要而又急需解决的技术问题. 本文在分析热浸镀锌时影响表面载锌量诸因素的基础上,探讨了增厚热镀锌层的工艺技术措施,为生产厚镀锌层和超厚镀锌层钢铁镀件提供必要的技术根据.     

热浸镀锌助镀剂及其助镀工艺的研究进展

综述了近年来热浸镀锌助镀剂及其助镀工艺的发展现状,给出了热浸镀锌常用助镀剂及其选择标准和作用机理,分析了助镀剂浓度、温度、铁盐含量和pH值等因素对热浸镀效果的影响,介绍了热浸镀中Zn-Al合金助镀剂、无铵助镀剂和电解活化助镀剂等新型助镀剂及其助镀工艺,指出了热浸镀助镀技术存在的问题和未来的发展方向。     

钢基热浸镀锌铝合金的研究

为进一步提高镀锌层质量和耐腐蚀能力,通过在传统热浸镀锌中添加少量铝,获得了钢基热镀锌铝合金层。研究了钢基热浸镀锌铝合金镀过程中,助镀剂的组成,镀液温度、浸镀时间、钢基硅含量等因素对镀层厚度的影响,获得了一种耐腐蚀性好,结合力强和光滑的热镀锌铝合金层,该锌铝合金镀层与镀锌层相比,在二氧化硫气氛中的耐腐蚀能力有很大的提高。     

热镀锌带钢表面缺陷形成分析及改进研究

结合首钢京唐二冷厂3号镀锌机组和4号镀锌机组线的生产工艺和设备,对热浸镀锌的锌灰形成机理进行了分析,对热浸镀锌带钢表面常见的几种缺陷的形成机理进行了分析重点叙述了锌灰导致露钢缺陷的形成过程,同时提出了改善热镀锌锌灰问题的工艺技术和首钢京唐相关设备优化趣崔。     

稀土在金属表面处理工艺中的应用技术(6)——稀土热浸镀锌

稀土在热浸镀锌工艺中的应用包括2个方面:热镀锌工件下锌锅前助镀时加入助镀剂中;加入熔融锌液中进行热浸镀锌.对这2个方面的应用试验表明,稀土在热浸镀锌工艺中的应用可以改善镀锌液的流动性,减少工件的上锌量,避免和减少厚边的产生;能净化热镀锌液,减少锌瘤和锌灰的产生,降低锌的无效损失;能提高钢铁件表面对锌的吸附性和结合力,提高热镀锌工件的整体耐腐蚀性和表面光洁度.同时简要介绍了稀土热镀锌的实际使用操作技术和注意事项.     

热镀锌钢板表面状况对漆膜性能的影响

热浸镀锌钢板表面粗糙度、无铬耐指纹钝化后锌层的均匀性及锌渣等表面状况直接影响着镀锌钢板漆膜层的各项性能;热浸镀锌钢板表面的粗糙度对钝化膜的性能有影响,进而影响耐指纹热镀锌钢板的涂漆附着力和耐蚀性能.采用SEM,EDS,EPMA等方法,对耐指纹热镀锌钢板进行分析,找出了漆膜性能与镀锌钢板表面粗糙度之间的关系,发现锌层的不...     

添加表面活性剂和亚铁盐助镀对热浸镀锌层耐蚀性能的影响

针对批量热浸镀锌传统氯化锌+氯化铵复盐助镀过程的氨氮烟尘污染问题,采用常用无机盐、稀土盐,添加3类表面活性剂和亚铁盐配制了系列无铵助镀液,采用电化学极化法和全浸试验法测试了系列无铵助镀液处理基础上所获得热浸镀锌层的耐腐蚀性能,分析了助镀剂中表面活性剂及亚铁盐对热浸镀锌层耐蚀性能的影响,采用金相显微镜观察分析了无铵助镀条件下镀层的组织结构。结果表明:在电化学和全浸试验中单纯加入表面活性剂时,镀层的耐蚀性有所降低,但通过在无铵助镀剂中加入一定量的亚铁盐可提高镀层的耐蚀性,其中FC09-Ⅱ系列中添加10 g/L亚铁盐、FC-3c系列中添加10 g/L亚铁盐、FC-3d系列中加入20 g/L亚铁盐得到的热浸镀锌层耐腐蚀性较好。     

钢材热浸镀低铝含量锌铝合金层的形成、影响因素及性能评价

热浸镀低铝含量锌铝合金的耐蚀性优良,铝含量对锌铝合金镀层的性能有较大影响。总结了热浸镀锌铝合金镀层的组成,对热浸镀锌铝合金低铝含量时镀层的形成过程进行了描述,分析了钢中Si,Mn,P等常规元素对锌铝合金镀层中Fe-Al金属间化合物形成的影响;阐述了热镀锌铝合金层的工艺特点及性能评价方法;指出了今后热镀锌铝系多元合金层的研究方向。     

汽车用合金化热镀锌板镀层剥离行为的分析

为了研究合金化热镀锌层与基体的剥离性能,设计了一种用于剥离合金化热镀锌层的特殊试验装置和专用胶.利用该装置可以在普通的万能拉伸仪上将合金化热镀锌层从镀锌板基体上剥离下来,同时测定出其镀层脱落过程的剥离力,发现镀层剥离时剥离力曲线趋于水平线.扫描电镜观察结果显示,镀层整体与基体分离,X射线衍射分析剥离前试样由г,г1,δ和α-Fe相构成,剥离后基体侧含有г,г1,α-Fe相,镀层侧只有г,г1和δ相.这说明合金化热镀锌层在外力的作用下出现了沿镀层与基体的交界层(г+г1)开裂而发生剥离.     

稀土、铝、镁对热镀锌基合金镀层耐蚀性能的影响

为得到耐蚀性较高的多元合金镀层,在Al-Zn,Zn-Mg镀液中加入了Re,Al,Mg元素,获得了7种热镀锌层.通过全浸加速腐蚀试验、盐雾加速腐蚀试验(NSS)和电化学试验(Tafel,EIS),研究了加入元素对热镀锌基合金镀层耐蚀性能的影响,并初步探讨了镀层的耐蚀作用机理.结果表明:Re,Al,Mg均能提高锌基镀层的耐...     

Growth and surface morphology of hot-dip Al–Si on 9Cr-1Mo steel

The high-temperature oxidation behavior of a commercial cold-rolled 9Cr-1Mo steel sheet that was hot-dipped in Al–7 wt.% Si was studied. The oxidation kinetics showed a two-stage behavior. The oxidation rate was significantly faster during the first hour, followed by a decreased steady-state growth rate at longer times. The hot-dipped steel had a higher oxidation rate than has been reported for FeAl alloys. During oxidation, many large pores and needles or rod-shaped FeAl were formed beneath the oxide scale. The formation of pores was attributable to the consumption of the limited aluminum that is caused by the outward diffusion of aluminum to form γ-Al₂O₃ and the inward migration of aluminum by Fe/Al inter-diffusion. The formation of γ-Al₂O₃ and internal voids filled with oxides in the aluminide layer was responsible for the increase in the rate of oxidation.     

Dissolution kinetics of iron in liquid zinc

In hot dip galvanizing, steel strip is coated by immersion in a bath of molten zinc. The principal reactions that occur at the steel/liquid zinc interface are (1) dissolution of iron and (2) nucleation and growth of intermetallic compounds. In order to improve the management of industrial galvanizing baths, it is essential to evaluate the flux of dissolved iron that diffuses into the bath from the sheet. For this purpose, a rotating disk device has been developed to study the dissolution and diffusion of iron in pure liquid zinc at the temperature usually employed in galvanizing baths (465°C). Since the dissolution reaction is controlled by diffusion under these conditions, the diffusion coefficient of iron in liquid zinc has been measured and found to be: D _Fe ^Zn(L) = (9.8 ± 0.1) × 10^–10 m²·s^–1     

Theoretical model of the interfacial reactions between solid iron and liquid zinc-aluminium alloy

Steel strip is often coated with a layer of zinc in order to protect it against corrosion. One of the most commonly used coating processes is continuous hot dip galvanizing. In this process, the steel strip is immersed in a molten zinc bath containing small amounts of aluminium (less than 1 wt%). A model has been developed describing the kinetics of the galvanizing reactions that occur at the steel/liquid zinc interface (dissolution of iron, heterogeneous nucleation and growth of the intermetallic phase designated Fe₂Al₅Zn _x ). The model has been validated using experimental data available in the literature for a classical galvanizing treatment that lasts three seconds.     

热浸镀铝层的性能研究

为研究热浸镀铝层的组织结构、耐腐蚀性和耐热性等表面性质，通过XRD和EPMA以及硬度测试等方法研究了热浸镀铝层的组织结构及其表面成分性能的变化、浸铝后扩散铝对表层组织及性能的影响，并对热浸镀铝层的耐蚀、耐热性及抗氧化性进行了论述。钢热浸铝后其组织由表面层、过度层及基体三部分组成，热浸铝试样的表面层几乎与铝液成分相同，由于Al、Fe相互扩散，浓度超伏，降温时易出现FeAl3相；过渡层中Al2Fe是主要生长相，AlFe相在过渡层的齿状根部至顶端出现。     

镧镨铈混合稀土对热浸渗铝的影响

镧普铈混合稀土（LPC）是新型专利成分的混合稀土。研究了LPC对热浸渗铝层组织和耐腐蚀性的影响。结果表明，在铝液中加入LPC，使渗层组织细化、均匀，渗层前沿整齐。加入LPC后，渗层无论是否经过扩散处理，耐蚀性能均明显提高。扩散前，其耐蚀性是不加稀土渗层耐蚀性的1．3倍，扩散后其耐蚀性是不加稀土渗层耐蚀性的3倍。     

大型钢管结构件热镀锌实践

大型钢管结构件在热镀锌时,易出现锌积块、镀层表面灰暗、镀层过厚、粘附性差等问题.为此,对热镀锌合理的结构设计和工艺过程的优化、行车操作等进行了讨论,叙述了热镀锌主要工艺步骤的注意要点.列举了典型件的工艺规范,提出了提高热镀锌质量的规范及措施.     

热镀锌清洁生产的实施与审核

我国是当今世界钢结构件热镀锌生产大国,热镀锌生产资源消耗大、污染严重,实施清洁生产是我国热镀锌行业可持续发展的唯一出路,而清洁生产的审核是实施清洁生产的必要途径.为此,分析了我国热镀锌清洁生产存在的主要问题,介绍了联合国商品共同基金(CFC)项目"中国热镀锌工业的技术转换及促进需求"在我国的实施情况,探讨了清洁生产的审核方法.     

Corrosion of ferrous- and zinc-based materials in CCA, ACQ and CuAz timber preservative aqueous solutions

Timber construction relies on connections between members. Traditionally, metallic nails and bolts are used for this. Previous research has shown that these metallic components are subject to corrosion in certain treated timbers. The American Wood Preservers’ Association AWPA E17-99 standard test has been applied using mild steel, hot-dipped galvanised steel (HDG) and 316 stainless steel coupons to examine the feasibility of using aqueous media to model corrosion rates of fastener materials in contact with timber electrolytes. In order to achieve this, comparison has been made with previously published research dealing with corrosion rates in solid timber electrolytes. The results of the corrosion testing in aqueous copper-chrome-arsenate (CCA), copper azole (CuAz) and alkaline copper quaternary (ACQ) timber preservative solutions show that aqueous electrolytes cannot be used to accurately model the corrosion behaviour of mild steel and HDG mild steel timber fixing materials. In contrast to the results obtained in treated timber, HDG steel was found to be the most active material in terms of overall metallic losses during exposure to the aqueous solutions. In addition, CCA was considerably more aggressive than either the CuAz or the ACQ preservatives. The results are discussed in terms of electrolyte pH, metallic passivation and the thermodynamic behaviour of the anodic and cathodic reactions at the mixed (corrosion) potential.