Al—Zn—Mg—Sc系热强可焊铝合金

将钪加入Al-Zn-Mg系合金中，可显著改善该系合金的许多重要的技术特性和使用性能。01970和01975合金就是在Al-Zn-Mg系基础上发展起来的高强可焊热强铝合金。不含钪的Al-Zn-Mg系合金尽管含有多种过渡金属元素锆和钛，以及铜，并使锌和镁的成分最佳比，各含2.6%,从而使合金的可焊性增强，但由于铜的加入，使合金焊接时生成裂纹的倾向增大了。采用添加钪元素后，将使由铜引起的焊接裂纹倾向完全消失。由于采用钪合金化元素，还进一步保证了晶粒的细化，保证了该合金系即使在铜含量处于高位时，也具有较高的抗焊接热裂纹特性。现将01970和01…     

Zn—Al合金热型连铸定向凝固的晶体生长机理

对热型连铸条件下Zn-Al系列合金引锭时的晶体形核和随后的本的竞争生长过程进行了探讨,组织观察表明,单向热流条件下引锭端部生核的晶粒当其枝晶择优生长方向与热流方向一致时才能生长,其它取向的晶粒逐渐被淘汰,合金的凝固特性对选晶过程有极大的影响,ZA5和ZA8合金由于凝固范围窄,晶体直接由引锭端部的晶粒通过竞争生长获得柱状晶组织,ZA12,ZA22和ZA27含Al量高,凝固范围宽,其平行柱状晶组织是从引锭端部的等轴晶区发展而来的。     

吸铸法制备Zr—Al—Ni—Cu—Mo大块非晶合金

采用吸铸方法制备了Zr60Al9Ni15Cu15Mo1五元合金,利用X射线、光学显微镜和差示扫描量热法研究了其结构和热稳定性。实验结果表明,该合金组织从宏观上看,几乎均由非晶相组成,其玻璃转变温度Tg、晶化温度Tx值分别为688和773K,过冷液相区宽度△Tx值为85K,表明了一个具有大的玻璃形成能力的五元非晶合金的形成,但与四元Zr-Al-Ni-Cu合金系相比,Mo的加入没有改善其玻璃形成能力。     

Pt—Pd—Rh合金的高温氧化

用ＴＧ热重仪测定Ｐｔ－Ｐｄ－Ｒｈ合金的挥发失重曲线，用Ｘ光电子能谱（ＸＰＳ）和溅射剥离技术确定其氧化态表层及次表层组元化学状态和浓度。结果表明合金挥发失重曲线遵循：Δｍ＝Ｋ０ｔ＾ｎ－直线失重规律。     

Al—Zn—Li—Mg—Cu合金在433K的时效行为

采用透射电镜（TEM）和Vickers硬度计研究了Al-Zn-Li-Mg-Cu合金在433K的人工时效行为,结果表明,在等温时效动曲线上存在双阶硬化行为。第一阶段硬化起因子合金基体上沉淀析出的δ′相（AlLi） 时效强化效果来自δ′相;随着时效的进行,到达第二时效硬化峰,在合金基体上除了δ′相外,大量析出一种具有准晶结构的沉硬化相（命名为X相）,此时,时铲强化效果来处自δ′相和X相,在X相的周围存在无δ′相析出区,表明X相含有Li原子,X相呈棒状,棒的长轴与基体的＜110＞Al方向一致,EDS测试表明,X相富集Cu,Zn和Mg。     

添加微量Sb对Mg—9Al—0.8Zn合金蠕变抗力及微观组织的影响

对Mg-9Al-0.8Zn－（0．1,0．4,0．7）Sb合金的高温蠕变性能及其微观组织进行了观察。结果表明,添加微量Sb可以显著提高Mg-9Al-0.8Zn（AZ91)合金在150－200℃区间的蠕变寿命,大幅度降低其稳态蠕变速率。使用扫描电镜和透射电镜观察分析了高温形变前后试样的显微组织及变化,在此基础上探讨了AZ91合金高温蠕变机制及添加Sb对其抗蠕变性能的改善机理。     

Zn含量及残余应变对Cu—8—13Zn合金电阻温度曲线的影响

研究了Zn含量及残余应变对Cu-8%～13%Zn合金电阻温度曲线的影响.结果表明CuZn合金电阻温度变量与Zn含量和残余应变无关,在0～150℃温度范围内,Cu8%～13%Zn合金电阻率变量与温度的关系可用△ρ△t=0.0073×10-6△t来计算.讨论了Matthissen定则在高浓度固溶体中的扩展应用.     

Al-Mg合金热力学性质的计算

以Ｍｉｅｄｅｍａ二元合金生成热模型为基础,结合一些基本热力学关系式,利用元素的基本性质计算了１０７３Ｋ下ＡｌＭｇ合金中组元Ｍｇ的活度及合金的部分热力学函数（ΔＨ,ＧＥ,ＳＥ）。结果表明,在１０７３Ｋ下,溶液中Ｍｇ的行为相对拉乌尔定律存在较大的负偏差;混合焓、过剩自由能与过剩熵在整个浓度范围内均为负值;混合焓最小值为－１１．４ｋＪ／ｍｏｌ,过剩自由能最小值为－８．７７ｋＪ／ｍｏｌ,过剩熵的绝对值较小,接近零。计算结果与实验数据吻合较好。     

热浸Zn-Ti合金镀层的耐腐蚀性能

为了抑制热镀锌过程中因含硅活性钢引起的镀层超厚生长,采用在纯锌浴中加Ti的方法,研究了热浸Zn-Ti合金镀层的耐蚀性能.采用浸泡腐蚀、电化学极化、交流阻抗以及X射线光电子能谱等方法,研究了热浸Zn-Ti合金镀层的耐蚀性能.结果表明:Zn-Ti舍金镀层在5%NaCl溶液中的自发腐蚀倾向小于Zn镀层,其极化电阻和交流阻抗增大,腐蚀电流密度减小,耐蚀性能提高.Zn-Ti镀层表面形成的氧化膜由ZnO和TiO2组成.Zn-Ti合金镀层的耐腐蚀性能优于纯锌镀层是由于在镀层表面形成了更加稳定的TiO2膜.     

化学镀制备Ni—Sn—Cu—P合金非晶形成能力

首次用化学镀方法制备了四元Ｎｉ－Ｓｎ－Ｃｕ－Ｐ合金镀层,用Ｘ光衍射及扫描电镜对合金镀层形貌和结构进行了测定,确定了不同工艺条件下的非晶合金形成区。用张邦维提出的非晶合金形成理论对Ｎｉ－Ｓｎ－Ｃｕ－Ｐ合金非晶形成能力及合金元素在非晶形成中的作用与机理进行了研究。     

三元系彩色热镀锌镀液的热力学性质

利用三元热力学性质的积分模型及活度系数解析式对Zn-Mn-Me和Zn-Ti-Me两系列三元合金镀液的组元活度及活度相互作用系数进行了计算．结果表明,Me为Ni和Cu时,均使呈色元素Mn或Ti的活度提高,Ni的影响程度比Cu显著得多;而Me为Ti和Mn时,Ti降低了Mn的活度;而Mn则提高了Ti的活度．通过与实验结果比较表明,镀液中溶质组元的活度与呈色效果之间有着必然的联系,即,凡是可以提高呈色元素活度的添加元素均有利于镀液综合性能的提高,从而最终优化呈色效果．因此,Mn,Ni和Cu均为彩镀液的有利元素,Ti的利弊与添加的相对量有关．     

机械镀Zn-Ti复合镀层的性能

在机械镀锌中添加钛盐,获得了Zn-Ti复合镀层,使得镀层具有比纯锌镀层更加优良的耐蚀性能.试验中利用体视显微镜、扫描电子显微镜观察分析了机械镀Zn-Ti复合镀层的表面形貌和断口结构,对其孔隙率、结合强度、耐腐蚀性等性能进行检测,并分析添加钛盐对镀层性能的影响.结果表明:机械镀Zn-Ti复合镀层是一种综合性能优良的防护镀层,比机械镀纯锌层外观更为均匀光滑,无贯穿性孔隙,结合力和耐腐蚀性均优于机械镀锌层.     

锌锰合金镀层钝化条件研究

为进一步提高Zn-Mn合金镀层的抗蚀性,采用绿色低铬钝化处理锌锰合金镀层,并对钝化条件进行优化,研究表明,Zn-Mn合金(未钝化)浸泡1 200h出现红锈,经绿色低铬钝化后,5%氯化钠水溶液浸泡1 500h后出现少量红锈,锌锰合金镀层经钝化后抗蚀性明显提高.     

Electrodeposition and characterization of Zn-Mn alloy coatings obtained from a chloride-based acidic bath containing ammonium thiocyanate as an additive

The electrodeposition of Zn-Mn alloys was performed using a chloride-based acidic bath containing ammonium thiocyanate (NH₄SCN) as an additive. An electrochemical study using cyclic voltammetry (CV), performed for each of the metal ions (Zn(II) and Mn(II)), showed that neither metal ion forms complexes with NH₃, and that Mn(II) but not Zn(II) forms complexes with SCN⁻. The influence of NH₄SCN on the morphology, composition and crystallographic structure of the electrodeposited Zn-Mn alloys was studied using scanning electron microscopy (SEM), glow discharge spectroscopy (GDS) and X-ray diffraction (XRD). The results show that the presence of NH₄SCN in the solution induces an increase in the Mn content of the alloy, from 3% in the Zn-Mn alloy obtained in the absence of additive to 6.2% in the alloy obtained in the presence of additive. In addition, the presence of NH₄SCN favors the formation of coatings comprised of a mixture of ε-phase Zn-Mn(002) + α-phase Zn-Mn(111) alloys. These coatings were compact and smooth and exhibited a lower corrosion rate compared to the coatings obtained in the absence of NH₄SCN, which where comprised of a mixture of Zn, ε-phase Zn-Mn and α-phase Zn-Mn alloys.     

镁锂合金表面锌锰磷化膜的制备与性能表征

采用化学转化法在镁锂合金表面制备了外观深灰色、结构均匀致密、耐蚀性能良好的锌锰磷酸盐转化膜,并研究了磷化温度对磷化膜性能的影响。采用扫描电子显微镜(SEM)、能谱(EDS)仪、X射线光电子能谱(XPS)和X射线衍射(XRD)仪对膜层的表面形貌、化学组成及结构进行了表征。采用动电位极化曲线、电化学交流阻抗(EIS)和腐蚀失重实验对磷化膜的耐蚀性进行了研究。结果表明,锌锰磷化膜主要由Zn、Zn3(PO4)2、MnHPO4、Mn3(PO4)2组成。锌锰磷酸化膜起到了保护镁锂合金的作用,提高了镁锂合金的耐蚀性,当磷化温度为45℃时,磷化膜的腐蚀电流密度最低,腐蚀速率最小,耐蚀性能最好。     

Study of Conversion Coatings on Zinc Deposition Obtained from Low Pollution Solutions

The electrochemical engineering and operation of a pilot plant for the electrodeposition of Zn-Mn alloys is described in this paper. The time-averaged current density (hence c.d.) distribution on the wire and the time evolution of the bath composition are modelled and compared with experiment. Electrodeposition experiments were performed at different c.d.s on several hundred meters of steel wire; the composition of the coatings as a function of c.d. is predicted with a simple electrochemical model, also taking into account mass transport at the wire, and compared with experiment. Structural and functional properties of the coatings were studied, some effects of drawing on the coating properties were measured. The surface morphology of Zn-Mn coatings on steel wires was studied by SEM, their crystallographic structure was investigated by XRD and their in-depth composition by AES. Corrosion resistance in neutral and alkaline solutions and corrosion effects on tensile properties of the coated steel wire were measured.     

Structure and composition of artificially synthesized rusts of Zn-Fe and Zn-Ti alloys

The artificial rusts of Zn-Fe and Zn-Ti alloys were synthesized from aqueous solutions of mixed metal chloride, sulphate, and nitrate such as ZnCl₂-FeCl₂, ZnSO₄-Ti(SO₄)₂, Zn(NO₃)₂-Fe(NO₃)₃, and so forth, and were characterized by a variety of techniques. Rust particles with different compositions and morphology were formed, strongly depending on the types of anions and metal ions. Sheet particles of basic zinc chloride (simonkolleite) were generated in the ZnCl₂-FeCl₂ system and the plate particles of basic zinc sulphate were formed in sulphate systems. These sheet or plate particles and the nanoparticles produced in Zn-Ti systems are expected to form compact rust layers by preferred orientation and dense packing, respectively, and contribute to a high corrosion resistance of Zn alloys.     

电泳涂装常温磷化工艺及磷化膜性能

在自制的低温锌系磷化液基础上,通过加入镍盐、锰盐和羧基聚合物,并以硝基苊为促进剂,研制出了一种适用于电泳涂装的低锌锰改性常温磷化工艺.用扫描电镜和能谱仪对低锌锰改性磷化膜与普通锌系磷化膜的形貌和组成进行对比分析.结果表明,该工艺制备出的磷化膜耐蚀性和耐碱性均优于普通锌系磷化膜;该磷化工艺可在常温下10min内在金属表面形成完整、致密、耐碱性好的磷化膜,它是由Zn3(PO4)2、FeZn2(PO4)2、Mn Zn2(PO4)2组成的椭球状磷酸盐晶体薄膜.     

Rapid solidification of Y3Al5O12 garnet from hypercooled melt

Containerless solidification of Y₃Al₅O₁₂ garnet (YAG) was carried out using an aero-acoustic levitator to elucidate the solidification process beyond the hypercooling limit (ΔT_hyp). A YAG melt was seeded at different undercoolings by a SiO₂ trigger needle. The apparent plateau after recalescence disappeared at around ΔT=500 K and the post-recalescence temperature (T_post) decreased from the melting point with further increase in undercooling. ΔT_hyp of YAG was estimated to be 769 K using the specific heat of liquid that was evaluated by a heat-transfer calculation from the obtained cooling curves. T_post decreased before reaching the estimated ΔT_hyp. Although this behavior was ascribed to heat extraction by the levitation gas, which suggests that the YAG melt did not solidify adiabatically due to the low thermal conductivity, the maximum undercooling of 1060 K indicates that the YAG melt solidified beyond ΔT_hyp. Moreover, the cellular morphology of YAG was observed even beyond ΔT_hyp. It can be seen that the cellular morphology is retained since the thermal supersaturation does not reach unity at ΔT_hyp due to the large kinetic effect.