工艺参数对38MnVS钢锰系磷化膜表面形貌和耐蚀性的影响

目的研究磷化温度和时间对38MnVS钢磷化膜表面形貌、膜厚和耐蚀性的影响,获得38MnVS钢锰系磷化的最佳工艺参数。方法通过控制单因素变量,在不同磷化温度和时间下在38MnVS表面制备锰系磷化膜。通过扫描电镜(SEM)、测厚仪和硫酸铜点蚀测试等方法,对38MnVS钢表面磷化膜形貌、膜厚及耐蚀性能进行了分析。结果 38MnVS钢表面磷化膜为非均匀形核,磷化膜晶粒首先形成于划痕和晶界处。随磷化时间延长,磷化膜晶粒迅速覆盖基体表面,磷化膜厚度和耐蚀性不断增加。当磷化时间大于15 min时,磷化膜性能变化不大。当磷化温度小于75℃时,不利于磷化膜的生长,磷化膜不能完全覆盖基体,磷化膜的厚度和耐蚀性较低。随磷化温度的升高,磷化膜晶粒不断长大,磷化膜厚度和耐蚀性迅速增加。当磷化温度超过95℃时,磷化膜性能增速下降。结论 38MnVS钢的最佳磷化工艺为:85℃,15 min。     

黑色磷化膜形成的因素分析

通过对黑色磷化膜形成的因素分析,采用控制磷化液的游离酸度,总酸度,磷化温度,以及工件的表面质量,解决了磷化液沉渣多,磷化膜结晶粗糙,外观颜色发灰等问题。     

高强双相钢表面选择性氧化行为对磷化性能的影响

目的确定高强双相钢表面Si、Mn元素选择性氧化行为对磷化性能的影响,以改善高强双相钢的磷化性能。方法在具备不同表面选择性氧化行为的试样表面制备磷化膜。采用X射线光电子能谱仪(XPS)、辉光光谱仪(GDS)、透射电镜(TEM)等手段,分析高强双相钢表面Si、Mn元素的选择性氧化行为,通过扫描电镜观察磷化膜的结晶状态,并采用电化学技术分析钢板在磷化液中的反应过程。结果当高强钢表面Si含量较少时,表面氧化物主要以弥散分布的小颗粒状Mn Al_2O_4形态存在,能够加快在磷化液中酸蚀反应速度,磷化晶粒均匀、致密,尺寸小于4mm,覆盖率为100%。当高强钢表面Si含量较高时,形成的Mn_2SiO_4容易在晶界聚集,颗粒尺寸较大,减慢了酸蚀反应速度,磷化晶粒尺寸大于8mm,均匀致密性差。而提高材料表面Mn元素的富集程度,可以减轻Mn_2SiO_4聚集的现象,提高酸蚀反应速度,磷化晶粒均匀、致密,尺寸小于4mm,覆盖率100%。结论减轻双相高强钢表面Si元素的富集程度,而提升Mn元素的富集程度,可以加快钢板在磷化液中的酸蚀反应,进而改善磷化性能。     

清洁型铁系磷化膜的常温制备与表征

Q235钢铁试片在以磷酸、钼酸铵等组成的铁系磷化液中常温快速磷化后,自然干燥8h以上,生成了免水洗的彩色磷化膜。用SEM和EDS对磷化膜进行形貌和元素含量分析。结果表明：免水洗的磷化膜由Fe^3＋的氧化物、磷酸盐及少量的钼酸盐等组成,膜晶粒尺寸≤3μm,膜连续、致密,膜重约0．8g／m^2,耐3％的NaCl溶液腐蚀约2h以上,喷涂铁红环氧底漆后附着力达1级。     

常温钢铁多功能磷化液

给出了能同时实现传统磷化四步效果的常温磷化液的基本组成.该磷化液得到的磷化膜结晶均匀,呈灰色,硫酸钢点滴时间在2 min以上,氯化钠浸泡6 h以上无锈迹出现.     

酒石酸钾钠对镁合金表面磷化膜耐蚀性的影响

为进一步提高镁合金表面磷化膜的耐蚀性,在磷酸二氢铵和高锰酸钾组成的磷化液中加入酒石酸钾钠,通过扫描电镜和能谱分析分别对磷化膜的表面形貌和组成元素进行观察和测试,通过电化学阻抗谱和极化曲线对磷化膜的耐蚀性进行考察。结果表明,酒石酸钾钠加入到磷化液中以后,磷化膜表面的微裂纹数量明显减少,表面更加平整、致密,膜电阻和电荷转移阻力明显增大,减少了腐蚀介质渗入到基体的通道,增大了腐蚀性离子的迁移阻力。同时,磷化膜中Mn、O和P等元素含量的增加,磷化膜中含有更多镁的磷酸盐和锰的氧化物,使磷化膜的耐蚀性进一步提高。     

中温锌一钙系黑磷化膜的制备与性能研究

为了改善锌-钙系黑色磷化膜的外观和性能,探讨了配方与工艺,采用扫描电镜(SEM)观察磷化膜表面微观形貌,X射线荧光光谱法(XRF)分析磷化膜成分,测试了膜层厚度、附着强度、耐磨性和耐蚀性能.结果表明:采用硝酸铜作发黑剂,Na2MoO4为氧化促进剂,经过硝酸铋预浸处理能够获得深黑色、防护性能良好的磷化膜.CaO的含量增加能改变膜表面晶体形貌,当氧化钙含量为30g/L时,晶体粒径明显减小,膜层中锌、钙元素含量增加,使耐磨性能和耐蚀性能提高.     

热镀锌层上磷酸锌转化膜的生长与耐蚀性

热镀锌钢板在pH3.0、45℃的磷酸锌溶液中磷化2～600s,用扫描电镜、能谱仪和X射线衍射仪分析磷化膜的组织形貌和成分,并探讨膜层的生长行为。结果表明:磷酸锌晶体在锌晶粒内及晶界处均可成核,开始是以接近平行的片状生长,并逐渐向多方向生长成扇骨状的晶片。随着磷酸锌晶体的成核和生长,磷化膜的覆盖率增加,但晶体之间的孔隙难以完全消除;长大的磷酸锌晶片容易折断脱落,导致磷化后期膜层的质量增量减小;磷化膜主要由Zn3(PO4)2.4H2O组成。热镀锌钢板经磷化处理后,耐蚀性显著提高,磷化膜的耐蚀性随磷化时间和膜层覆盖率的增加而提高。     

常温磷化膜的性能及表面形貌研究

在常温磷化膜的研制过程中，用４Ｘ型显微镜对各种膜层进行了组织形貌的观察和研究。结果表明，通常有八种因素影响常温磷化膜的形成、外观、膜重以及耐蚀性等。通过对膜层性能及形貌研究得知，对常温磷化处理工艺进行优化，可使覆膜质量明显提高。     

稀土促进的钢铁表面磷酸盐转化膜形成

探讨了在硝酸盐-锌系磷化过程中稀土化合物、溶液酸碱度、时间对磷化膜外观、膜重和耐蚀性的影响.结果表明,把少量稀土化合物(REC)添加到磷化液中可显著提高磷化膜的耐蚀性和磷化速度,其较佳的投加量为30 mg/L～55 mg/L.      

Study of role of phosphate coating properties on electrophoretic paint performance by EIS and simulated corrosion tests

The influence of phosphate bath chemistry on phosphate coating properties and, eventually, on corrosion resistance properties of electrophoretic (ED) painted steel samples was examined. Two types of zinc phosphate bath chemistry with different concentration of zinc and nickel ions, and different values of total acid, free acid, and accelerator content were studied. The phosphate bath with higher value of acid ratio (total acid/free acid), nickel ion concentration, and accelerator point produced the best phosphate coating on steel surface with globular microstructure, small crystal size, high P ratio, and uniform coverage. Phosphate coated and only alkali cleaned samples were cathodic ED painted. Their corrosion resistance properties were evaluated by salt spray test, cyclic corrosion test and electrochemical impedance spectroscopy. The relative increase in corrosion resistance of painted sample due to best phosphate coating was 1·4 to 1·8×. Paint adhesion of samples significantly deteriorated when painted without phosphate pretreatment.     

磷酸铝铸铁高温涂料的研制

研究用磷酸铝作粘结剂配制铸铁件用高温涂料。采用震动法紧实涂料骨料,将紧实体积密度与松装体积密度对比,按照对比结果确定最佳颗粒配比,配制成涂料。生产试用表明,该涂料强度高,耐磨性好,适用于高要求的灰铸铁、球铁铸件。     

Effect of Mg2+ on the microstructure and corrosion resistance of the phosphate conversion coating on hot-dip galvanized sheet steel

The effect of Mg²⁺ in the phosphate solution on the microstructural evolution and corrosion resistance of the coating on hot-dip galvanized steel has been explored. Surface morphology observations reveal that increasing the solution Mg²⁺ concentration increases the population density and refines the grain size of the phosphate grains. In the presence of Mg²⁺, the phosphate coating is composed of mixed Zn phosphate hydrate and (Zn, Mg) phosphate hydrate. Furthermore, elevating Mg²⁺ in the solution reduces the porosity of the phosphate coating. As a result, the corrosion resistance of the phosphate coating is improved.     

Q235钢表面氩弧熔覆TiC复合涂层的组织与性能

以Ti粉、C粉、Fe粉为原料,利用氩弧熔覆技术在Q235钢表面原位合成了TiC增强Fe基复合涂层,分析了涂层的显微组织和物相,测定了涂层的硬度。结果表明:复合涂层与基体界面无气孔、裂纹,呈冶金结合;熔覆层组织由树枝晶、等轴晶组成,TiC主要分布于晶粒内和晶界处;涂层显微硬度随TiC含量的增加而增大。     

双阴极等离子溅射沉积TiC薄膜对金刚石工具性能的影响*

采用双阴极等离子溅射沉积方法对金刚石颗粒表面进行镀TiC处理。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)进行形貌和物相分析。使用金刚石单颗粒静压强度测定仪和人造金刚石冲击强度测定仪检测金刚石的静压强度和冲击韧性。以相同型号和粒度的普通金刚石颗粒为对比样品,讨论了镀TiC处理对金刚石工具的影响。结果表明,金刚石表面形成了一层均匀且致密的TiC薄膜,该薄膜以柱状方式沿垂直于金刚石表面方向生长。在镀层的保护下,金刚石的单颗粒强度和冲击韧性得到了提高。由于镀层改善了金刚石对胎料的润湿性,金刚石工具的冲击强度和抗弯强度也得到了提高。     

大气等离子喷涂的YSZ纳米热障涂层的微观结构

采用YSZ(8％Y2O3-Zr02，质量分数)纳米粉末，经大气等离子喷涂(APS)方法制备得YSZ纳米热降涂层(TBC)．喷涂前的粉末额粒直径为30—50nm，晶粒尺寸约12nm．对涂层的分析结果表明：YSZ纳米涂层平均晶粒尺寸在20—30nm，有个别粗晶直径达200—300nm．涂层由立方相c—ZrO2和四方相t′—ZrO2组成，t′相内存在畴结构．涂层内孔洞细小弥散，多呈闭合式．TEM下可见位错缠结和富层错的板条带结构．     

Microstructure and mechanical properties of interface between laser cladded Hastelloy coating and steel substrate

In order to improve the corrosion resistance of carbon steel, Hastelloy coatings were prepared on E235 steel substrate by a high power diode laser with laser scanning speeds of 6 and 12 mm/s, respectively. The interface between the coating and substrate was firstly exposed by dissolving off the substrate. Its microstructure, composition and mechanical properties were systemically studied. Special “edges” along the grain boundary were found at coating/substrate interface. These “edges” consisted of intergranular corrosion area and real grain boundary. The interface of coating mainly displayed austenite structure ascribed to the rapid solidification as well as the dilution of Ni during preparation. Additionally, Hastelloy coating and its interface prepared at the speed of 12 mm/s showed higher hardness than that prepared at the speed of 6 mm/s. Grain boundaries had higher friction coefficient than grains at both coating/substrate interfaces. Moreover, the interface at higher laser scanning speed exhibited smaller grains, lower dilution rates of Ni and Fe as well as a better tribological property.     

Effect of Sn content on microstructure and tensile properties of as-cast and as-extruded Mg−8Li−3Al−(1,2,3)Sn alloys

The effects of Sn content on microstructure and tensile properties of as-cast and as-extruded Mg−8Li−3Al− (1,2,3)Sn (wt.%) alloys were investigated by X-ray diffractometry (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and tensile test. It is found that, as-cast Mg−8Li−3Al−(1,2,3)Sn alloys consist of α-Mg+β-Li duplex matrix, MgLiAl₂ and Li₂MgSn phases. Increasing Sn content leads to grain refinement of α-Mg dendrites and increase in content of Li₂MgSn phase. During hot extrusion, complete dynamic recrystallization (DRX) takes place in β-Li phase while incomplete DRX takes place in α-Mg phase. As Sn content is increased, the volume fraction of DRXed α-Mg grains is increased and the average grain size of DRXed α-Mg grains is decreased. Increasing Sn content is beneficial to strength but harmful to ductility for as-cast Mg−8Li−3Al−(1,2,3)Sn alloys. Tensile properties of Mg−8Li−3Al− (1,2,3)Sn alloys are improved significantly via hot extrusion and Mg−8Li−3Al−2Sn alloy exhibits the best tensile properties.     

超细晶钢微观组织与力学性能的各向异性研究

通过温轧技术,成功制备了平均晶粒尺寸约1μm的超细晶钢。利用扫描电镜、电子背散射衍射和室温拉伸等检测手段,研究了超细晶钢板的微观组织与力学性能的各向异性。结果表明：制备的超细晶钢板不同方向的微观组织和力学性能具有明显的各向异性;纵截面表层和心部的晶粒大多呈现拉长的形态,同时表层的晶粒拟合椭圆长/短轴比相较于心部更小,形状更加接近于圆形,横截面的晶粒拉长状特征相较于纵截面减弱,更接近等轴态,晶粒在三维空间呈细长的扁梭形态;各向强度由高到低依次为轧向、横向、与轧向成45°方向;长梭形晶粒组成的微观组织形态和织构是导致超细晶钢板力学性能各向异性明显的主要原因。     

Mg元素对热浸镀锌基合金镀层组织结构的影响

采用热浸镀方法在Q235钢板表面制备了Mg的质量分数分别为0.0%,0.1%,0.3%,0.5%的锌基合金镀层。利用扫描电子显微镜(SEM)、能谱仪(EDS)、辉光光谱仪(GDOES)等手段分析了Mg含量变化对镀层组织结构的影响。结果表明:随着镀层中Mg含量的增加,合金镀层的表面晶粒逐渐变小;Mg元素富集于晶界之中,起到细化晶粒的作用;Mg推迟了ζ相向δ相的转变,使镀层结构中的δ相层减薄。