焊接电流和药皮厚度对水下湿法焊接熔渣物相及微观组织的影响

文中采用自制的金红石型药皮焊条进行水下湿法焊接,重点分析了焊接电流和药皮厚度对熔渣物相及微观组织的影响.对熔渣的宏观形貌分析发现,当药皮厚度较薄时,焊后熔渣稀薄,覆盖不均匀,此外,焊接电流对焊接飞溅有重要影响,当焊接电流较大时,焊接过程中有大量飞溅产生.通过对熔渣的碱度系数及物相分析得出,熔渣的主要组成相为FeTiO₃和CaTiO₃,还有少量的MnTiO₃,FeF₃和Ca-Si-O相,药皮厚度和焊接电流对熔渣的碱度系数和组成相影响均较小.熔渣的微观组织分析发现,减小药皮厚度和增大焊接电流,熔渣中生成大量的树枝状组织,熔渣微观组织的方向性增强,有利于脱渣.     

含钛夹杂物对连铸保护渣性能的影响

含钛钢连铸过程中析出氮化钛夹杂,并参与渣-金界面反应,严重恶化传统含钛钢连铸保护渣的理化性能。研究了不同含量的TiN和TiO₂对不同碱度保护渣的熔点、黏度、结晶比例以及凝固温度等性能的影响规律。测试结果表明,TiN对CaO-SiO₂基保护渣的性能影响最大,随着渣中TiN含量的升高,保护渣的黏度、结晶比例和凝固温度大幅度升高;当TiN质量分数大于5%时,熔点大幅升高。TiO₂对CaO-Al₂O₃基保护渣的性能影响最大,当TiO₂质量分数小于4%时,可小幅度降低保护渣的黏度和凝固温度;当TiO₂质量分数大于10%时,渣中钙钛矿成为主要析出物相,熔渣的性能严重恶化,影响对坯壳的润滑作用。通过对比3种不同碱度的基础渣发现,CaO-SiO₂-Al₂O₃基保护渣具有较好吸收含钛夹杂物的能力。     

萤石对水下湿法焊接工艺性能及力学性能的影响

采用自制金红石型碳钢焊条进行水下湿法焊接,重点分析药皮中萤石与大理石的加入量对焊缝成形,熔渣成分、物相、覆盖性、脱渣性及焊接接头力学性能的影响。由焊缝宏观形貌分析发现,随着药皮中萤石含量的增加,焊缝的铺展性和熔渣的脱渣性变好,但熔渣的致密性和覆盖性变差。通过对熔渣的物相进行分析,得出熔渣的主要组成相为Fe_2MnTi_3O_(10)和FeTiO_3,还含有少量的MnO和Ca_2SiO_4,改变萤石和大理石的含量,对熔渣的主要组成相没有产生影响。通过力学性能测试得出,药皮中萤石加入量为6.5%时,所得焊接接头的力学性能最好。     

TiO2和Al2O3对CaO-SiO2-CaF2基础焊接渣系熔化特性的影响

研究了TiO₂和Al₂O₃对CaO-SiO₂-CaF₂基础焊接渣系黏度、熔化温度、表面张力等熔化特性的影响，并利用XRD和拉曼光谱分析四元焊渣的物相和结构特征.结果表明，TiO₂含量增加会显著降低焊接熔渣黏度、熔化温度及表面张力，提升熔渣流动性；Al₂O₃含量增加会使焊接熔渣黏度、熔化温度及表面张力先略有升高后明显降低.CaO-SiO₂-CaF₂-TiO₂和CaO-SiO₂-CaF₂-Al₂O₃四元焊渣完全熔化后，其黏度均在0.2 Pa·s以下，继续升温对黏度无显著影响，低于熔化温度后，焊渣随温度降低迅速凝固，呈明显的短渣特性.经XRD和拉曼光谱分析可知，四元焊接熔渣中主要含具有硅酸盐网络结构的Ca₄Si₂O_...     

熔渣成分和微观结构对自保护药芯焊丝脱渣性的影响

采用SEM,XRD对X80管线钢用碱性自保护药芯焊丝的焊后熔渣进行了分析,研究了熔渣化学成分、熔渣微观组织结构对脱渣性的影响. 结果表明,BaO,TiO2的复合相在熔渣中占有较大比重,在造渣及脱渣中起着重要作用;随着熔渣中TiO2含量的增加,CaO,SiO2含量的减少,熔渣的微观组织结构由小颗粒状逐渐转变为非等轴的针状、棒束状、小块儿状,熔渣的方向性变强,内部结合力增大,同时,能形成尖晶石的自由氧化物减少,熔渣与焊缝金属之间的结合力降低,粘渣变少,脱渣性变好;当熔渣中TiO2/CaO比值达到4～6,同时将SiO2/CaO比值控制在1～2时,能获得较好的脱渣性.     

A102不锈钢焊条脱渣性影响因素的研究

分析了Ａ１０２不锈钢焊条熔渣宏观断口形貌和微观结构对脱渣性的影响,研究认为,熔渣微观结构中,当球状ＦｅＯ数量少而基体中结构呈方向性较强的骨架状或枝状结构时脱渣性能较好。     

钛铁矿焊条脱渣性改善的研究

通过对钛铁矿焊条药皮的优化设计及对脱渣性的系统研究,探讨了焊缝表面粘渣的机制及其影响因素。熔渣的微观组织结构对焊条脱渣性的影响较大。适当的TiO_2/FeO比值是避免焊缝表面粘渣的重要因素。     

TiO2对不锈钢焊条脱渣性的影响

运用均匀设计的方法,将药皮敷料作为自变量,焊缝的脱渣性作为目标函数,探讨了药皮敷料对不锈钢焊条脱渣性的影响,给出了二者间的关系曲线;根据计算分析结果,研究了对焊缝脱渣性影响较大的两种敷料,即金红石和钛白粉.它们的含量(主要成分为TiO2)增加时,在熔渣的微观结构中形成呈树枝状或方向性较强的骨架状结构,主干尺寸长、分枝面积大而密的白色相增多,不锈钢焊条的脱渣性能变好.     

超超临界汽轮机转子FB2钢电渣重熔熔渣析晶行为研究

采用了热力学软件Factsage计算、熔渣差热分析(DSC)及高温水淬渣XRD、SEM-EDS分析相结合的方法，对超超临界汽轮机转子FB2钢电渣重熔用熔渣的析晶动力学及析晶行为进行了研究，预测了电渣重熔过程中渣皮成分，为后续超百吨级电渣锭电渣重熔过程中修正渣皮形成对熔渣成分影响，实现全重熔周期稳定化冶炼技术攻关奠定了基础。研究结果表明：在10℃/min的冷却速率下，熔渣至少有3种晶相析出；CaF₂作为初晶相，在熔渣中质量占比最大，而Ca₁₂Al₁₄F₂O₃₂、MgO则作为针状、孤岛状分布在CaF₂基体中；Ca₃B₂O₆析晶温度偏低(1000℃附近),此时熔渣处于半凝固状态，组元迁移速率较低，Ca₃B₂O₆晶相在渣中完全弥散分布，且尺寸较小；CaF₂析晶机制为三维生长机制，在冷却过程中均匀形核，并随温度降低...     

纳米TiO2颗粒对Ni-W-P合金镀层性能的影响

目的 探究纳米TiO₂颗粒对Ni-W-P镀层组织结构、耐蚀性与耐磨性能的影响,提高2024铝合金管材的耐蚀性。方法 使用化学镀的方法在2024铝合金表面制备了Ni-W-P/TiO₂纳米复合镀层,通过SEM、EDS、XRD表征了镀层的表面形貌、表面元素分布以及镀层物相。对比了传统Ni-W-P镀层与所制备Ni-W-P/TiO₂纳米复合镀层的显微硬度与耐磨性。结果 加入纳米TiO₂颗粒后,镀层表面变得更加致密,晶粒得到细化。EDS结果表明,纳米TiO₂颗粒在镀层中分布均匀。物相分析表明,镀层为晶态结构,加入纳米TiO₂颗粒后,镀层平均晶粒尺寸为9.706 nm,比Ni-W-P镀层的晶粒尺寸减小了0.612 nm。失重试验表明,Ni-W-P/TiO₂纳米复合镀层在Cl^–为2×10⁵ mg/L的地层水中具有较强的耐蚀性,腐蚀速率为0.1062 g/（m²·h）,与Ni-W-P镀层...     

高脱渣率烧结焊剂熔渣晶体类型及其成分分布

通过均匀设计方法,以脱渣性为目标,对高碱度MgO-Al₂O₃-CaO渣系进行优化,并试验测定了脱渣率.在此基础上分别采用SEM观察熔渣晶体微观组织形貌及其特征、EDAX测定熔渣不同微区的成分含量、XRD确定熔渣的物相组成.发现脱渣率较高的10号焊剂的熔渣主要由含Zr,Mg,Ca,Al及Si元素的复合岩石相构成,熔渣不同微区的元素含量差别很大,形成了锆型雪花晶、镁型十字晶及钙型树枝晶.锆型和钙型晶体能够阻碍镁型晶体的生长,锆还起到细化镁型晶体的作用.结果表明,通过提高焊剂中大理石及锆英砂的含量使熔渣中镁型晶体微观组织的连续性和方向性发生改变,是改善脱渣性的一种有效途径.     

Sinterability and dielectric properties of Ba0.55Sr0.4Ca0.05TiO3-CaTiSiO5-Mg2TiO4 composite ceramics

The composite ceramics of Ba_0.55Sr_0.4Ca_0.05TiO₃-CaTiSiO₅-Mg₂TiO₄ (BSCT-CTS-MT) were prepared by the conventional solid-state route. The sintering performance, phase structures, morphologies, and dielectric properties of the composite ceramics were investigated. The BSCT-CTS-MT ceramics were sintered at 1100 °C and possessed dense microstructure. The dielectric constant was tailored from 1196 to 141 as the amount of Mg₂TiO₄ increased from 0 to 50 wt%. The dielectric constant and dielectric loss of 40 wt% Ba_0.55Sr_0.4Ca_0.05TiO₃-10 wt% CaTiSiO₅-50 wt% Mg₂TiO₄ was 141 and 0.0020, respectively, and the tunability was 8.64% under a DC electric field of 8.0 kV/cm. The Curie peaks were broadened and depressed after the addition of CaTiSiO₅. The optimistic dielectric properties made it a promising candidate for the application of tunable capacitors and phase shifters.     

保护气体对含铌不锈钢药芯焊丝347L脱渣性的影响

研究了不同保护气体CO2,Ar和混合气体(CO2 Ar)对347L型含铌不锈钢药芯焊丝脱渣性的影响,并在相同的条件下对自制的GDQA347L(3号)与TFW-347L和AT-Y347L型两种不锈钢药芯焊丝的脱渣性进行了对比,深入分析了熔渣的宏观形态和微观组织对脱渣性的影响.结果表明,研制的GDQA347L焊丝在Ar气保护下的脱渣性最好,混合气体保护下的脱渣性次之,CO2保护气体的脱渣性最差,由于CO2气体在高温下变为活性气体的,具有很强的氧化性,容易造成脱渣困难;三种焊丝在不同保护气体下熔渣的微观组织形态所表现的规律基本上一致,在熔渣微观组织中,当其条带状体的尺寸长、面积大时,对脱渣有利.     

Fe掺杂TiO2纳米材料的合成及光催化性能

以钛酸丁酯为钛源,Fe(NO3)3·9H2O为铁源,采用溶胶-凝胶法制备Fe/TiO2纳米粉体,利用溶胶结合静电纺丝技术制备Fe/TiO2纳米纤维,从材料改性及形貌改善两个角度共同提高TiO2纳米材料的光催化活性及实用性。借助XRD、SEM、TEM等分析技术,探究了Fe/TiO2纳米材料在可见光区的光催化活性,分析了煅烧温度及掺铁量对Fe/TiO2纳米材料光催化性能的影响。结果显示,铁的掺入及形貌的改善有助于提高TiO2的光催化性能。     

TiO2纳米粒子对铝锂合金微弧氧化膜结构及性能的影响

为改善微弧氧化膜层的耐蚀性及力学性能,向电解液中添加TiO₂纳米粒子后对2297铝锂合金进行了微弧氧化。利用SEM、XRD、EDS、辉光放电表征技术及电化学测试技术,分析了TiO₂纳米粒子对微弧氧化膜结构、力学性能及耐蚀性的影响。结果表明：添加TiO₂纳米粒子后,微弧氧化膜层变得平坦致密。随着TiO₂纳米粒子添加量的提高,膜层表面放电通道的孔径逐渐减小,数量逐渐增多。TiO₂纳米粒子会抑制熔融Al₂O₃与电解液中$ {\rm{SiO}}_{\rm{3}}^{{\rm{2 ^- }}}$的接触,所以膜层中Si元素的含量随TiO₂纳米粒子添加量的增加而逐渐下降(原子数分数从初始的10.27%下降到了3.10%)。显微硬度测试结果表明,TiO₂纳米粒子的引入增加了膜层的致密度及平整度,所以膜层的硬度得到了提升(添加1 g/L TiO₂纳米粒子后硬度提高了15%)。电化学测试结果显示,当微弧氧化的其它条件相同时,TiO₂纳米粒子的适量添加会提升膜层的耐蚀性,但过量添加时,由于膜层放电通道数量的增多等原因,其耐蚀性下降。     

Microstructural characterization of plasma sprayed Al2O3-40 wt.% TiO2 coatings on high density graphite with different post-treatments

Graphite is one of the candidate materials proposed for application in pyrochemical reprocessing plants involving aggressive molten chloride environment. Post treatments are promising techniques for the improvement of properties of thermal spray coatings for different industrial applications. In the present work, the effect of post treatments like vacuum annealing (VA) and laser melting (LM) on the microstructure and chemical modification of plasma sprayed Al₂O₃-40 wt.% TiO₂ coatings over high density (HD) graphite substrates has been investigated. When compared with sprayed coatings (SC), VA coatings showed cluster morphology and LM coatings exhibited homogenous microstructure. On laser melted surfaces networks of cracks were observed. XRD studies showed that the metastable γ-Al₂O₃ phase present in the SC is transformed to stable α-Al₂O₃ after post treatments. In LM coatings Al₂TiO₅ phase was more predominant in contrast to SC and VA coatings. The microhardness enhancement was observed in case of LM coating compared to the VA and SC. Due to elimination of coating defects in LM samples, there is a considerable reduction in the surface roughness.     

Microstructure characterization and photocatalytic activity of mesoporous TiO2 films with ultrafine anatase nanocrystallites

A series of mesoporous TiO₂ films on borosilicate glass with ultrafine anatase nanocrystallites were successfully synthesized using a non-acidic sol gel preparation route, which involves the use of nonionic surfactant Tween 20 as template through a self assembly pathway. The microstructure of these TiO₂ films was characterized by XRD, SEM, HR-TEM, UV-Vis spectroscopy, and N₂ adsorption-desorption isotherm analysis. Their photocatalytic activities were investigated by using creatinine as a model organic contaminate in water. It was found that all mesoporous TiO₂ films prepared with Tween 20 exhibited a partially ordered mesoporous structure. The photocatalytic activity of the TiO₂ films could be remarkably improved by increasing Tween 20 loading in the sol at the range of 50% (v/v), which yielded large amount of catalyst (anatase) on the glass support and enhanced specific surface area. The optimum Tween 20 loading was 50% (v/v) in the sol, above which good adhesion between TiO₂ films and borosilicate glass could not be maintained. The final TiO₂ film (Tween 20: final sol = 50%,v/v) exhibits high BET surface area (∼ 120 m²/g) and pore volume (0.1554 cm³/g), ultrafine anatase nanocrystallinity (7 nm), uniform and crack free surface morphology, and improved photocatalytic activity.     

Photoresponse and donor concentration of plasma-sprayed TiO<Subscript>2</Subscript> and TiO<Subscript>2</Subscript>-ZnO electrodes

The photoelectrochemical characteristics of plasma-sprayed porous TiO₂, TiO₂-5%ZnO, and TiO₂-10%ZnO electrodes in 0.1 N NaOH solution were studied through a three-electrode cell system. The microstructure, morphology, and composition of the electrodes were analyzed using an electron probe surface roughness analyzer (ERA-8800FE), scanning electron microscopy, and x-ray diffraction. The results indicate that the sprayed electrodes have a porous microstructure, which is affected by the plasma spray parameters and composition of the powders. The TiO₂-ZnO electrodes consist of anatase TiO₂, rutile TiO₂, and Zn₂Ti₃O₈ phase. The photoresponse characteristics of the plasma-sprayed electrodes are comparable to those of single-crystal TiO₂, but the breakdown voltage is close to 0.5 V (versus that of a saturated calomel electrode). The short-circuit photocurrent density (J _SC) increases with a decrease of donor concentration, which was calculated according to the Gartner-Butler model. For the lowest donor concentration of a TiO₂-5%ZnO electrode sprayed under an arc current of 600 A, the short-circuit J _SC is approximately 0.4 mA/cm² higher than that of the TiO₂ electrodes under 30 mW/cm² xenon light irradiation. The J _SC increases linearly with light intensity. The original version of this paper was published as part of the DVS Proceedings: “Thermal Spray Solutions: Advances in Technology and Application,” International Thermal Spray Conference, Osaka, Japan, 10–12 May 2004, CD-Rom, DVS-Verlag GmbH, Düsseldorf, Germany.     

新渣系碱性焊条脱渣性分析

分析了多种国内外碱性焊条药皮渣系,设计了新的渣系.用均匀设计的思想方法和计算机软件来安排试验.选定9种药皮辅料作为自变量,并把每个自变量分成6个水平,共做了24个焊条小样.利用计算机统计分析脱渣性数据.结果给出了自变量与因变量之间的数学模型和趋势图.它们揭示出内在规律:多种药皮辅料对焊缝脱渣性的影响呈交互作用的形式,其中大理石与碳酸钡、硅灰石与铝镁粉、金红石与铁粉之间两两的交互作用都会使焊缝脱渣性提高;而铝镁粉与萤石、铝镁粉与碳酸钡之间两两的交互作用都会使焊缝脱渣性降低.