Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion

Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturing was employed to fabricate pure Zn with a heterogeneous microstructure and exceptional strength-ductility synergy.An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99%using a laser power range of 80∼90 W and a scanning speed of 900 mm s−1.The Zn sample printed with a power of 80 W at a speed of 900 mm s−1 exhibited a hierarchical heterogeneous microstructure consisting of millimeter-scale molten pool boundaries,micrometer-scale bimodal grains,and nanometer-scale pre-existing dislocations,due to rapid cooling rates and significant thermal gradients formed in the molten pools.The printed sample exhibited the highest ductility of∼12.1%among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength(∼128.7 MPa).Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternative arrangement of bimodal Zn grains with pre-existing dislocations.Additionally,continuous strain hardening was facilitated through the interactions between deformation twins,grains and dislocations as strain accumulated,further contributing to the superior strength-ductility synergy.These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications.

ELECTRODEPOSITION OF CORROSION-RESISTANT ZINC-ALLOY POWDER FROM ALKALINE SOLUTION

Mercury free zinc alloy powder were electrodeposited from alkaline solution. Additives containing lead, indium or bismuth were added in the electrolyte and zinc powders with corresponding compositions were obtained. The relations between adding amounts of additives and the contents of corresponding compositions in zinc powder are not linear. Aluminum and calcium cannot be co deposited with zinc. Electrodeposition effectively reduced the contents of harmful impurities. Gas evolution of electrodeposited Zn Pb In Bi alloy powder was less than that of atomized mercury free alloy powder.

THERMAL DECOMPOSITION OF ZINC CARBONATE HYDROXIDE HYDRATE POWDERS OF DIFFERENT PARTICLE SIZE AND SAMPLE MASS

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Effect of zinc powder content on tribological behaviors of brake friction materials

Brake friction materials with different zinc powder contents(0,2,4,6,8 wt.%)were fabricated via powder metallurgy method.The results indicate that with the increasing zinc powder content,the density and thermal conductivity of the materials gradually increase,while the hardness decreases monotonously.With increasing zinc powder content,the curve of the nominal friction coefficient shows fluctuating trend but the lowest friction coefficient also shows an increase.However,the wear rate and braking noise of the friction material monotonously decrease with increasing zinc content.This effect may be attributed to the transformation of the tribological mechanism from adhesive wear and abrasive wear to adhesive wear.The brake friction material with 4 wt.%zinc powder exhibits both the best tribological and noise performance.

Electrodeposition of Corrosion Resistant Zinc Powder

Zinc powder electrodeposited from suspension bath has higher corrosion resistance than that from conventional bath. The results of X ray, SEM and EIS (Electrochem. Impedance Spectrum) indicated that the microstructures of zinc powder could be modified according to the kinds of suspension species. Suspension of TiO 2, SiO 2, In 2O 3, PbO 2 and SnO 2 could obviously improve the polarization resistance of zinc powder anodes in 5 mol/L KOH solution.

The effects of dietary supplementation with mushroom or selenium enriched mushroom powders on the growth performance and intestinal health of post-weaned pigs

Background There is an urgent need to identify natural bioactive compounds that can enhance gastrointestinal health and promote pig growth performance in the absence of pharmacological levels of zinc oxide(ZnO).The objectives of this study were to:1)compare the effects of mushroom powder supplemented with inorganic selenium(inSeMP)to mushroom powder enriched with organic selenium(orgSeMP)to pharmacological levels of ZnO on growth performance and faecal scores(FS)for the first 21 d post-weaning(Period 1);and 2)compare the molecular and microbial effects of inSeMP and orgSeMP in these pigs on d 39 post-weaning(Period 2).Methods In Period 1,pigs(3 pigs/pen;8 pens/treatment)were assigned to:(1)basal diet(control);(2)basal diet+zinc oxide(ZnO)(3100 mg/kg d 1–14,1550 mg/kg d 15–21);(3)basal diet+mushroom powder supplemented with inorganic selenium(inSeMP)containing selenium(selenite)content of 0.3 mg/kg feed;(4)basal diet+mushroom powder enriched with organic selenium(orgSeMP)containing selenium(selenocysteine)content of 0.3 mg/kg feed.Mushroom powders were included at 6.5 g/kg of feed.Results In Period 1,there was no effect of diets on average daily gain(ADG)and gain:feed(G:F)ratio(P>0.05).The orgSeMP supplemented pigs had a lower average daily feed intake(ADFI)compared to all other groups(P<0.05).The ZnO supplemented pigs had reduced FS compared to the basal and mushroom group,while the orgSeMP supplemented pigs had lower FS compared to the basal group during the 21 d experimental period(P<0.05).In Period 2,there was no effect of diets on ADFI,ADG and G:F ratio(P>0.05).The orgSeMP supplementation increased the caecal abundance of bacterial members of the Firmicutes and Bacteroidetes phylum,including Lactobacillus,Agathobacter,Roseburia,and Prevotella and decreased the abundance of Sporobacter compared to the basal group,while inSeMP increased the caecal abundance of Prevotella and decreased the caecal abundance of Sporobacter compared to the basal group(P<0.05).Dietary supplementation with inSeMP increased expression of TLR4 and anti-inflammatory cytokine gene IL10 and decreased nutrient transporter gene FABP2 compared to the orgSeMP group(P<0.05).Conclusion OrgSeMP is a novel and sustainable way to incorporate selenium andβ-glucans into the diet of weaned pigs whilst improving FS and modulating the caecal microbiota.

Determination of the density of zinc powders for alkaline battery

The density of zinc powder for alkaline battery was determined using a pyknometer.The results showed that powders made before the end of 2003 could reach relative densities above 99% of the theoretical density.Investigating the relative volume swelling of electrolysed gels of zinc powders,no evident relation between swelling and pyknometer density was found.

锌浮渣干湿法处理工艺对比与干法处理工艺关键设备选型及应用

在湿法炼锌的工业生产中,电解阴极锌片在熔锌感应电炉内熔化除杂时产出副产品锌浮渣,锌浮渣中含锌约80%,其中70%以上锌以单质形态存在。本文对比了干法和湿法两种处理工艺的优缺点,重点介绍了干法处理工艺中关键设备选择和能力计算,并结合实际生产情况对投产后的工艺设备进行改进和完善。

冷涂烯锌涂料的制备与性能研究

首先研究了不同环氧树脂(E20、E44和E51)对环氧含锌涂层基本性能的影响,其次探究了纯薄石墨烯的添加对涂层防腐蚀性和力学性能的影响,确定了锌质量分数30%涂料体系中纯薄石墨烯的最佳添加量,最后考察了膨润土、聚脲、聚酰胺钠作为防沉体系对冷涂烯锌涂料贮存稳定性的作用。通过中性盐雾试验,并结合扫描电镜、表面电阻率、剩余锌含量和力学性能测试,制备出符合T/CHTS 10105—2023标准要求的冷涂烯锌涂料。结果表明:采用环氧树脂E44所制备的涂层基本性能最佳;加入质量分数0.5%纯薄石墨烯后,涂层的力学性能均有提升,表面电阻率≤10^(6)Ω,锌粉利用率超过80%,耐中性盐雾时间可达3000 h;添加质量分数0.9%膨润土、0.6%聚脲和1%聚酰胺钠防沉体系后,冷涂烯锌涂料可在50℃下稳定贮存60 d。

Ge and Cu recovery from precipitating vitriol supernatant in zinc plant

A novel technology using Fe powder as reducing agent for Ge and Cu recovery from precipitating vitriol supernatant in Zn hydrometallurgical plant was investigated. The results show that reaction time, temperature, agitation speed, initial pH value of solution and the amount of reducing Fe have significant effects on recovering Ge and Cu, and the optimum process operating parameters are established as follows： time 120 min, initial pH value 1.5, the dosage of reducing Fe powder 4 g/L, agitation speed 600 r/min and temperature 80 °C. Under these experimental conditions, the recovery ratios of Ge and Cu from precipitating vitriol supernatant in Zn hydrometallurgical plant can reach 96% and 100%, respectively. The content of Ge in the reduced residue reaches up to 2.06% （mass fraction）, indicating that the separation and enrichment of Ge from the Zn sulfate solution is realized. The grade of Ge and Cu can reach up to 4.88% and 56.75%, respectively, when the reduced residue is further processed.

锌硒配施对水稻汞的阻隔效应

【目的】研究锌硒配施对土壤-水稻体系中水稻富集转运汞的影响,探讨锌硒配施对水稻汞的阻隔效应,为汞污染土壤安全利用提供参考。【方法】选取贵州铜仁碧江区某矿区汞污染土壤,以水稻品种川康优727为研究对象,采用盆栽试验,测定水稻生长发育特征以及土壤有效汞和水稻各器官汞含量。【结果】锌硒配施使土壤中有效汞含量显著降低了45%-75.2%,低浓度硒与锌配施使土壤有效汞含量降低75.2%;锌硒配施使水稻各器官汞降低了15.2%-92.3%,其中,籽粒汞含量的降幅效果最好(87.6%-92.3%)。除高浓度硒和高低浓度锌配施促进了水稻汞从根到籽粒转运外,锌硒配施对水稻富集与转运汞的阻隔效果均优于锌、硒单施,锌硒配施使水稻汞从根到籽粒的富集系数降低了88%-92%,低浓度硒与高低浓度锌配施对水稻汞从根到籽粒的转运系数分别降低了69.2%和61.5%。【结论】锌硒配施对水稻汞的阻隔效应显著,有效缓解了汞对水稻生长发育的毒害作用。

Preparation of high purity cadmium with micro-spherical architecture from zinc flue dust

This research has focused on the treatment of zinc flue dust by an acid leach process, combining an environmentally suitable impurity removal process to recover cadmium. Optimum conditions were found as follows： H2SO4 concentration 90 g/L, liquid/solid ratio 6：1, leaching temperature 60 ℃ and leaching time 1.0 h. Under these conditions, 95.8% cadmium was recovered. FeAsO4 and Fe（OH）3 precipitates with FeCI3 are found to be highly effective to obtain a high degree of separation of heavy metals and the oxyanions of arsenic from the leachate. The overall separation of arsenic and other heavy metals and precipitate settling rates are optimum at n（Fe）/n（As） ratio of 3：l and pH 6. The removal rates ofFe, Pb and Cu from the solution were greater than 98.9%, and As removal rate was 99.6%. A solvent extraction with P204 was used for the separation of zinc and cadmium. Optimum conditions are obtained as follows： 20% P204 （volume fraction） diluted with kerosene at room temperature, pH 3.0, and varying organic/aqueous （O/A） phase ratio 1：1. The extraction rate of zinc is 99.2% under these conditions. Spherical cadmium particles showing nearly uniform size were produced by hydrogen reduction at 310 ℃ and the crystal structure was cubic. In addition, the purity of the recovered cadmium powder is more than 99.99%.

锌冶炼副产物制备硫化锌吸附剂脱除气态汞的研究

基于以废治废的理念,以锌冶炼过程中产生的高硫渣和次氧化锌为原料,通过高温硫化的方式制备金属硫化锌吸附剂,采用X射线衍射(XRD)、拉曼光谱(Raman)、扫描电子显微镜(SEM)和比表面积分析(BET)等方法对不同焙烧温度和焙烧时间下制备的硫化锌吸附剂进行表征分析,并考察不同烟气温度和烟气成分对吸附剂脱汞性能的影响.实验结果表明:在焙烧温度和保温时间分别达到250℃和60 min后可实现硫化锌吸附剂的成功制备,且表面形成大量的介孔孔洞;制备的ZnS-250℃-90 min具有最佳的吸附性能,在烟气温度150℃以内,对气态单质汞(Hg^(0))的平均吸附效率在99%以上,且对烟气中的O_(2)、SO_(2)和H_(2)O具有较高的抗性;在模拟锌冶炼烟气成分和半穿透条件下,ZnS-250℃-90 min对Hg^(0)的吸附容量可达3.04 mg·g^(-1),优于常规金属硫化物吸附剂;硫化锌吸附剂表面的不饱和短链硫(Sx2-)为Hg^(0)的关键活性位点,其可与烟气中的Hg^(0)反应化学吸附反应,形成稳定的HgS,从而实现烟气中Hg^(0)的净化;采用热脱附和多硫化物浸渍可实现吸附剂的循环再生,五次循环后吸附剂对Hg^(0)的吸附效率保持在98%以上,汞以单质汞的形式得到回收.本研究不仅为锌冶炼行低成本汞污染控制和汞资源化利用提供了基础,也为锌冶炼废弃物再利用提供支撑,促进锌冶炼行业的绿色生产.

石墨烯锌粉涂料技术和应用进展

石墨烯锌粉涂料体现了新材料、新机理和卓越性能的特征,成为涂料行业的一个突破性创新。文章综述了石墨烯锌粉涂料的技术发展和应用现状。石墨烯独特的原子片层结构和不可渗透性,以及优异的力、热、电性能,贡献了石墨烯锌粉涂料新的防护机理。石墨烯的物理屏蔽作用、活化锌粉作用以及增强力学强度作用,在高性能石墨烯锌粉涂料中发挥了主导作用。石墨烯锌粉涂料优先物理屏蔽主导防护机理,与传统环氧富锌涂料优先阴极保护机理有着本质差异。石墨烯锌粉涂料在防腐性能、力学性能、施工性能以及节约锌粉和节能降碳等方面,均体现出明显优势,石墨烯低锌和石墨烯锌粉双涂层更具有创新优势。总结了近期石墨烯锌粉涂料在桥梁、风电、化工、水电、建筑、集装箱等领域的应用案例和现状。最后,指出石墨烯锌粉涂料技术和替代传统环氧富锌涂料的应用发展趋势,以及对钢结构长效保护的技术创新价值。

锌铝粉包覆改性对无铬达克罗涂层耐蚀性的影响

使用硅烷偶联剂KH570对片状锌粉进行表面包覆改性,同时使用正硅酸乙酯(TEOS)、乙烯基三异丙氧基硅烷(VIPOS)和丙烯酸(AA)对片状铝粉进行单层和复合包覆改性,以改性的锌粉和铝粉作为基础组成部分制备了无铬达克罗涂层,测定了改性锌铝涂层在3.5%NaCl溶液中的动电位极化曲线。结果表明:所制备的TEOS/VIPOS改性铝粉涂层的表面平整光滑,没有明显颗粒,涂料的分散性和稳定性较好;与未改性锌铝涂层相比,TEOS/VIPOS和TEOS/VIPOS/AA改性铝粉涂层的腐蚀速率明显下降,TEOS/VIPOS改性铝粉涂层具有较小的腐蚀电流密度(1.01μA/cm2)和腐蚀速率(0.011mm/a)。在20%硝酸铵溶液中浸泡2h后,TEOS/VIPOS改性铝粉涂层的表面平整光滑,耐蚀性较好。

氢化物发生-非色散原子荧光光谱法测定粉饼化妆品中Pb,As和Hg含量

建立并优化了氢化物发生-非色散原子荧光光谱法(HG-NDAFS)测定10种粉饼化妆品中铅(Pb),砷(As)和汞(Hg)的含量。确定了较佳载气流速为400 mL/min,屏蔽气流速为800 mL/min。优化了负高压和灯电流,确定了原子化器高度为8 mm。优化还原剂体系时,选择了质量分数1.5%KBH4溶液。载流选择2.4 mol/L HCl。结果显示,Pb,As,Hg的加标回收率分别为83.44%~90.32%,83.22%~86.59%,81.43%~89.94%,加标回收率良好。10种粉饼中共检出2种粉饼中含有Pb(含量0.48和0.27 mg/kg),1种粉饼中含有As(含量0.62 mg/kg),1种粉饼中含有Hg(含量0.11 mg/kg)。10种粉饼中的Pb,As,Hg含量均未超标。本研究建立的HG-NDAFS测定粉饼化妆品中Pb,As和Hg含量的方法准确度高,可用于粉饼化妆品中Pb,As和Hg含量的检测。

添加剂浓度对锌粉电沉积机理及晶体取向的影响

针对电解法制备锌粉时晶粒生长择优取向问题,选择新型添加剂对沉积过程的晶体取向影响进行研究。以四正丁基氯化铵为研究对象,利用电化学分析和DFT理论计算推断锌沉积机理,通过SEM、XRD、粒度分析等手段对晶体取向、粒度分布和微观形貌等进行表征。结果表明,在电流密度600 A/m^(2)、25℃及锌浓度为20 g/L的碱性溶液中进行电解制备锌粉的成核过程以瞬时成核为主,Zn(NH_(3))_(4)^(2+)在(101)面和(002)面的吸附能分别为-3.56 eV和-1.84 eV,容易形成(101)面的择优取向。四正丁基氯化铵的加入促进了锌沉积阴极极化,其在(101)面的较大吸附能,吸附在(101)面后隔绝了对锌的吸附,当添加剂浓度为20 mg/L时,得到粒度为32.44μm、(002)面织构系数为66.73%的片状锌粉,有望在锌离子电池中解决锌枝晶的问题而被广泛应用。

磷酸绝缘包覆对铁硅铝磁粉心的影响

以破碎铁硅铝合金粉为原料,通过调节磷酸用量和引入Zn2+对粉末进行化学绝缘包覆,制备了铁硅铝磁粉心。采用FESEM、XRD、同步热分析仪、B-H分析仪等检测设备,对粉体形貌、物相、热稳定性和磁粉心磁性能、电性能进行表征和检测。结果表明:Zn2+的引入能有效改善铁硅铝颗粒表面绝缘层形貌,形成的绝缘层由纳米级网状结晶磷酸盐组成,致密、均匀地分布在颗粒表面,在有效降低磁粉心功率损耗的同时,提升了磁导率。

锌冶炼烟气中汞、三氧化硫净化技术的研究进展

冶炼过程产生的烟气中含有高浓度二氧化硫(SO_(2))及不同形态的汞,同时伴有较高浓度三氧化硫(SO_(3))。烟气汞若处置不当,容易进入其他介质而产生二次污染;而烟气中SO_(3)是污酸产生的根本原因,且汞的存在加剧其治理难度。随着有色金属冶炼行业污染物排放标准的日趋严格,控制冶炼烟气汞和SO_(3)已成为行业亟待解决的难题。根据锌冶炼烟气汞、SO_(3)排放特征,通过总结汞形态转化和污染物分布规律以及冶炼行业中汞和SO_(3)污染控制技术的研究进展,提出对烟气汞及SO_(3)干式捕集的控制策略。

锌粉中含铝时金属锌含量的测定

锌粉中金属锌含量的测定多采用高锰酸钾间接滴定法,若试样中含有金属铝时,则先采用高锰酸钾间接滴定法测定出锌粉中的锌铝合量,再采用比色法测定出试样中的金属铝含量,最后将铝以1∶3.6352(质量分数比)换算成等量的金属锌予以扣除,即得样品中金属锌含量,多个样品检测结果的相对标准偏差0.13%~0.36%。该方法适用于锌粉生产、研究企业和检验检测机构。