通过制备非晶涂覆钢丝提高钢丝抗腐蚀性能（英文）

为了提高钢丝的耐腐蚀性能,使用连续涂覆工艺制备一系列锆基非晶合金(Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5))_(100-x)Nb_x(x=0,3,5,8,at%)涂覆Q195钢丝。相分析结果表明,涂层主要由非晶基体和一些金属间化合物组成;阳极极化实验发现所有非晶涂覆钢丝表现钝化行为,具有高的点蚀破钝电位和低的腐蚀电流。随着非晶涂层中铌含量增加,非晶涂覆钢丝的钝化区宽度增加,点蚀破钝电位升高。电子能谱分析发现,非晶涂覆钢丝抗点蚀性能提升可能与金属铌元素容易钝化,形成稳定钝化膜,同时能够稳定锆、钛,降低相分离有关。     

镍基非晶合金涂层的制备与腐蚀性能

用气体雾化法制备了Ni53Nb20Ti10Zr6Co6Cu3非晶合金粉末,将粒度小于25μm的非晶粉末用动力金属喷涂工艺制备了非晶涂层．研究表明,非晶涂层厚度约500μm,涂层的空隙率随喷涂温度和沉积率的增加而减少．涂层腐蚀性能的评价选用1kmol／m^3 HCl水溶液,动电位极化曲线测量表明,随着空隙率的减少,涂层呈现出与非晶合金相当的优良耐蚀性能．     

Sol-gel法镁合金表面制备SiO2涂层及其腐蚀性能研究

利用有机醇盐水解法制备了SiO2溶胶,采用溶胶-凝胶法在AZ91D镁合金表面制备了SiO2涂层.通过SEM、XRD等分析技术对涂层表面结构和组织进行表征,并探讨了该涂层的耐腐蚀性能及涂覆次数对腐蚀性能的影响.结果表明:以正硅酸乙酯为原料、无水乙醇为溶剂、盐酸为催化剂,可制备出均匀透明的SiO2溶胶;3.5％NaCl水溶液浸泡腐蚀试验表明,SiO2涂层显著提高了镁合金表面的耐腐蚀性能.     

硅烷偶联剂KH550对正硅酸乙酯杂化涂层抗腐蚀性能的影响

利用电化学测试和扫描电镜(SEM)研究了硅烷偶联剂KH550对正硅酸乙酯(TEOS)杂化涂层的改性.结果表明:添加硅烷偶联剂能够明显提高TEOS杂化涂层的耐腐蚀性和降低涂层开裂倾向;经180℃热处理制备的KH550改性涂层性能最佳,在3.5%NaCl溶液中的腐蚀电流密度约为2.701×10-9 A/cm2,较铝合金基体...     

超声化学镀对烧结钕铁硼磁体抗腐蚀性能的影响

采用超声波化学镀方法,研究了在频率为40 kHz超声波条件下化学镀Ni-P合金对烧结NdFeB磁体抗腐蚀性能的影响,测定了超声功率对沉积速度和镀层磷含量的影响,观察了超声场对镀层表面形貌和Ni-P镀层耐腐蚀性的影响.结果表明,随着超声功率的增大,沉积速度增加,而镀层磷含量略有降低.与无超声场下的Ni-P化学镀层相比,超声条件下化学镀Ni-P合金组织更加细小,排列更加紧密,有更加优良的耐腐蚀性,能有效的保护NdFeB磁体.     

Al-Cr涂层的制备及抗热腐蚀性能研究

采用粉末包埋法在Ni基高温合金K417G上制备Al-Cr涂层,并研究其在25%NaCl＋75%Na2SO4（mass%）盐膜下900℃的热腐蚀特性.采用两步法沉积的Al-Cr涂层为双层结构,外层为β-NiAl相和少量AlCr2相,平均Cr含量约为20 mass%;内层为互扩散带.而采用一步法沉积的Al-Cr涂层具有三层...     

Cr元素对Fe基块体非晶合金形成能及腐蚀性能影响的研究

利用微合金化技术,制备了Fe_68.4-xCo_7.6Si₇B₁₀P₅C₂Cr_x (x=0, 1, 2, 3)非晶合金,并分别使用单辊急冷甩带法和铜模铸造法制备了带状和棒状样品。借助XRD、DSC、DTA表征该非晶合金系的热力学性能与非晶形成能;并进一步采用电化学动电位极化曲线法研究了该非晶合金系在硫酸溶液中的的耐腐蚀性能。实验结果表明,通过微量添加Cr元素的方法,使该合金系的非晶形成能普遍提高,当Cr元素添加量为2%时,获得了该系列非晶合金中的最大过冷液体区间(ΔTx=57K),并且成功制备了直径为5mm的圆棒状样品;同时,由于Cr元素的添加,在1N浓度的硫酸溶液中,材料表面上形成富含Cr元素的保护层,可以有效阻止材料内部的进一步腐蚀,耐腐蚀性能明显得到改善。     

铀表面鎏镀锌涂层及其抗腐蚀性能

利用锌汞齐在铀表面鎏镀锌保护涂层,利用扫描电子显微镜(SEM)、X射线能谱(EDS)对涂层进行了表征,采用热重法和激光拉曼光谱测试了涂层的抗氧化腐蚀性能。结果表明,在铀表面鎏镀的锌涂层结构致密,与基体结合紧密;在40%的氧气氛中,150℃温度时的加速腐蚀试验结果显示,鎏镀锌涂层具有优良的抗氧化腐蚀性能,锌涂层的抗腐蚀原理是基于在锌涂层表面形成致密的氧化锌保护膜,从而阻止基体铀的进一步腐蚀。     

热处理态NiCoCrAlY涂层的抗中性盐雾腐蚀性能

通过500 h中性盐雾试验研究了在低膨胀高温合金GH907上低压等离子喷涂(LPPS)的NiCoCrAlY涂层在热处理后的抗腐蚀性能,并与热处理态的LPPS制备的NiCr涂层的抗腐蚀性能进行了对比.结果表明,盐雾腐蚀500 h后,NiCoCrAlY涂层在扫描电镜下可以看到几个无破坏性作用的腐蚀坑,涂层表面仍保持较好的完整性和光洁性,对腐蚀产物的EDS面扫描表明腐蚀产物主要为Al的氧化物,涂层的腐蚀保护等级仅下降到9级;而NiCr涂层的表面出现了较多的腐蚀斑点,涂层的完整性和均匀性均已经被破坏,涂层表面产生了腐蚀裂纹,其腐蚀等级下降到4级.EDS分析表明腐蚀产物主要为Ni、Fe、Co等的氧化物.对比结果表明,NiCoCrAlY涂层表现出比NiCr涂层更强的抗中性盐雾腐蚀性能.     

Zr基和Ti基块体非晶合金的电化学腐蚀性能(英文)

用电化学方法研究Ti基和Zr基非晶合金及与非晶成分相同的Zr基晶态合金在1mol/LH2SO4和3.5%NaCl溶液中的腐蚀行为。极化曲线测试结果表明:在H2SO4溶液中,Zr基非晶和晶态合金自腐蚀电位比Ti基非晶合金的低;在NaCl溶液中,Zr基晶态合金的自腐蚀电位最低,而且在腐蚀过程中没有发生钝化,然而非晶合金都表现出钝化特性。交流阻抗测试结果表明:在NaCl溶液中非晶合金比晶态合金表现出更好的耐腐蚀性能,但是在H2SO4溶液中并没看到它们之间有明显的区别。表面形貌分析表明:在NaCl溶液中,这2种非晶合金都发生点蚀,而在H2SO4溶液中所有试验合金都表现出类似的特征,试样表面基本保持平整,只是在腐蚀表面的局部区域有一些裂纹出现。     

体能量密度对SLM成形316L不锈钢耐腐蚀性的影响

为了探究不同体能量密度对SLM成形316L不锈钢耐腐蚀性的影响,采用正交试验法制备不同激光功率、扫描间距和扫描速度下的SLM 316L不锈钢成形件,利用扫描电镜和电化学试验对其微观组织和自腐蚀电位进行观察和测量。结果表明,体能量密度过大或过小时,成形件表面的气孔和孔洞等缺陷较多,自腐蚀电位减小,耐腐蚀性变差。体能量密度为44.64 J/mm^-3时,SLM 316L不锈钢成形件的自腐蚀电位最高,组织表面的气孔等缺陷相对较少,耐腐蚀性最好。激光功率、扫描间距和扫描速度对SLM 316L不锈钢成形件的耐腐蚀性影响的次序为:激光功率＞扫描间距和扫描速度,最佳的工艺参数组合为激光功率250 W,扫描间距0.14 mm,扫描速度800 mm/s。     

Study on corrosion behavior of continuous bulk metallic glass-coated steel wire composite

Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 (atomic percent) (Vit1) Bulk metallic glass (BMG)-coated steel wire composite was produced by using continuous process. The existence of amorphous structure in the BMG coating was proved by differential scanning calorimeter (DSC) measurement and transmission electron microscope (TEM). The corrosion behaviors of the bare steel wire and the wire composite in 3.5 wt% NaCl solution corrosive media were investigated by immersion tests and electrochemical polarization measurements at room temperature. Scanning electron microscopy (SEM) was utilized to examine morphology of the corroded surface. By comparing the corrosion behaviors of the wire composite and the bare steel wire as well as the Vit1 BMGs reported in the literatures, the results of the present investigation reveal (1) it is important to choose sound technical parameters such as processing temperature to avoid the crystallization for the BMG coating of steel wire (2) the Vit1 BMG-coated steel wire composite has better corrosion resistance than the bare steel wire from perspective of either mass loss or polarization behavior (3) strong protective layers grow on the surface of the coated steel wire by anodization, of which the barrier effect to initiate pitting is slightly lower than that of the monolithic Vit1 BMG, but the general polarization behavior is quite similar to that of the monolithic Vit1 BMG.     

Influence of microstructure on the corrosion resistance of hyperduplex stainless steel

Hyperduplex UNS S32707 is a newly developed austenitic–ferritic stainless steel. The steel contains about 27%Cr, 7%Ni, 4.5%Mo, and 0.4%N, which results in a pitting resistance equivalent factor (PRE) equal to 49. In this study, the pitting corrosion resistance of this new grade of stainless steel was investigated by varying the microstructure using different thermal processes. The critical pitting temperature measurement and cyclic polarization tests confirm the high corrosion resistance of the hyperduplex steel in the solution treated condition. However, deleterious phases form easily during thermal processing and cause a drastic decrease in the corrosion resistance.     

Improvement on the pitting corrosion resistance of 304 stainless steel via duplex passivation treatment

A remarkable improvement in the pitting corrosion resistance of 304 stainless steel was attempted using a novel duplex passivation treatment method. First, chemical passivation in nitric acid followed electrochemical passivation via potential polarization of step cycling in sodium nitrate electrolyte. Compared with traditional chemical passivation, breakdown potential was increased from 0.31 V_SCE to positive than 0.9 V_SCE at 70°C in a solution bearing 0.6 M [Cl^?] concentration. The critical pitting temperature was enhanced from 21.5°C to above 70°C in a solution with 6 M [Cl^?] concentration. Impedance analysis and X‐ray photoelectron spectroscopy results show that a more compact passive film with a higher ratio of chromium oxide on iron oxide was achieved by electrochemical passivation compared with chemical passivation. Morphology observation suggested that the potential polarization of step cycling slightly increased the dissolution of inclusions after being subjected to chemical passivation. The probable reason for the improvement on pitting resistance is discussed in detail based on inclusion dissolution and the protectiveness in passive film.     

Zr基块体非晶合金的摩擦磨损行为(英文)

采用销盘式摩擦实验研究Zr基块体非晶合金分别在空气与氩气环境中的摩擦磨损行为。结果表明,在16N和23N2种不同载荷下,非晶试样在氩气中的磨损量都比在空气中的低45%以上。通过X射线衍射仪、差示扫描量热分析仪、扫描电子显微镜和光学表面轮廓仪等检测分析手段对磨损试样摩擦面的形貌和微观结构进行表征,发现在空气中磨损试样的表面存在大量摩擦颗粒和犁沟,而氩气中的试样表面相对平滑;非晶试样的磨损机理在空气中以磨粒磨损为主,而在氩气中则为粘着磨损。     

Effect of silicate pretreatment, post-sealing and additives on corrosion resistance of phosphated galvanized steel

Sodium silicate （water glass） pretreatment before phosphating, silicate post-sealing after phosphating and adding silicate to a traditional phosphating solution were respectively carried out to obtain the improved phosphate coatings with high corrosion resistance and coverage on hot-dip galvanized（HDG） steel. The corrosion resistance, morphology and chemical composition of the coatings were investigated using neutral salt spray（NSS） tests, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. The results show that pretreatment HDG steel with silicate solutions, phosphate coatings with finer crystals and higher coverage are formed and the corrosion resistance is enhanced. Adding silicate to a traditional phosphating solution, the surface morphology of the coatings is nearly unchanged. The corrosion resistance of the coatings is mainly dependent on phosphating time. Phosphating for a longer time （such as 5 min）, the corrosion resistance, increasing with concentration of silicate, is improved significantly. Post-sealing the phosphated HDG steel with silicate solutions, the pores among the zinc phosphate crystals are sealed with the films containing Si, P, O and Zn and the continuous composite coatings are formed. The corrosion resistance of the composite coatings, related to the pH value, contents of hydrated gel of silica and Si2O^2- 5 and post-sealing time, is increased markedly. The improved coatings with optimal corrosion resistance are obtained for phosphating 5 min and post-sealing with 5 g/L silicate solution for 10 min.     

ZrCuNiAl块体非晶合金的低温压缩变形行为

采用Instron 5500万能试验机对Zr55.7Cu23Ni9Al12.3块体非晶合金进行了应变速率为4×10-4 s-1、环境温度为143 K的低温压缩试验,研究了其低温压缩变形行为。结果表明,当测试环境温度从298 K（室温）降低到143 K时,该合金的强度和塑性均呈增加的趋势,且未出现传统晶态材料的冷脆性现象。分析表明,其屈服强度的增加源于低温下剪切带的形核需要更高的载荷,而低温下断口侧面高密度剪切带的形成导致了其塑性的增加。     

Estimation of Gibbs free energy difference in Pd-based bulk metallic glasses

A new thermodynamic expression for Gibbs free energy difference AG between the under-cooled liquid and the corresponding crystals of bulk metallic glasses was derived. The newly proposed expression always gives results in fairly good agreement with experimental values over entire temperature range between the fusion temperature Tm and the glass transition temperature Tg of Pd40Ni40P20, Pd40Cu30Ni10P20 and Pd43Cu27Ni10P20, which possess different heat capacities. However, the TS and KN expressions cannot always provide results in good agreement with the experimental values. In addition, the deviations between the experimental values and the AG calculated by the proposed expression at Tg are smaller than those given by other expressions for all the bulk metallic glasses studied.     

Effect of metalloid elements on magnetic properties of Fe-based bulk metallic glasses

In this work, we successfully prepare Fe₈₀(P, C, B)₂₀ bulk metallic glasses (BMGs) with the different content of P, C, B by combining fluxing treatment and J-quenching technique, and the effects of the metalloid elements (P, C, B) on the thermal stability and magnetic properties of the present Fe₈₀(P, C, B)₂₀ BMGs are investigated systematically. It is found that the replacements of P or B by C and P by B enhance the thermal stability of Fe₈₀(P, C, B)₂₀ BMGs. The substitutions of B for C or P and C for P result in the increase of both the saturation magnetization and the Curie temperature of Fe₈₀(P, C, B)₂₀ BMGs.