Preparation and properties of Ni-coated WC powder and highly impact resistant and corrosion resistant WC-Ni cemented carbides

WC powders were uniformly coated by Ni nanoparticles through a combined chemical co-precipitation and subsequent high temperature hydrogen reduction strategy(abbreviated as CM-WCN),and then were consolidated by vacuum sintering at 1450°C for 1 h to obtain WC−Ni cemented carbides.The microstructure and properties of the as-consolidated CM-WCN were investigated.The average grain size of WC in the consolidated CM-WCN was calculated to be in the range of 3.0−3.8μm and only few pores were observed.A relative density of 99.6%,hardness of HRA 86.5 and bending strength of 1860 MPa were obtained for the CM-WCN−10wt.%Ni,and the highest impact toughness of 6.17 J/cm^(2 )was obtained for the CM-WCN−12wt.%Ni,surpassing those of the hand mixed WC−Ni(HM-WCN)cemented carbides examined in this study and the other similar materials in the literature.CM-WCN cemented carbides possess excellent mechanical properties,due to their highly uniform structure and low porosity that could be ascribed to the intergranular-dominated fracture mode accompanied by a large number of plastic deformation tears of the bonding phase.In addition,the corrosion resistance of CM-WCN was superior to that of HM-WCN at the Ni content of 6−12 wt.%.

Influence of Impact Energy on Impact Corrosion-abrasion of High Manganese Steel

The impact corrosion-abrasion properties and mechanism of high manganese steel were investigated under different impact energies. The result shows that the wearability of the steel decreases with the increase of the impact energy. The dominant failure mechanism at a lower impact energy is the rupture of extrusion edge along root and a slight shallow-layer spalling. It transforms to shallow-layer fatigue flaking along with serious corrosion-abrasion when the impact energy is increased, and finally changes to bulk flaking of hardened laver caused by deeo work-hardening and heaw corrosion-abrasion.

Microstructure Evolution of 690 TT Heat Transfer Tube Under Impact Slip Dual-Axis Fretting Corrosion in High Temperature and High Pressure Water Environment

The service water environment of high temperature and high pressure was simulated for the steam generator heat transfer tube of pressurized water reactor.690 TT alloy tube and 405 SS plate were used to form the friction pair for impact slip dual-axis fretting corrosion experiments.The microstructure evolution of 690 TT alloy tube during dual-axis impact slip fretting corrosion was investigated.White light interferometer,scanning electron microscope,transmission electron microscope,and Raman spectrum were used to investigate the microstructure and abrasive products of the abraded surface and near-surface.Results indicate that within 105 cycles,the wear mechanism of 690 TT alloy tube is mainly adhesive wear accompanied by material transfer.With the increase in cycles from 5×10^(5) to 2×10^(6),the wear mechanism of 690 TT alloy tube is mainly crack initiation,propagation,and delamination.In terms of microstructure evolution,mixed layer exists under the three body layer in the cross-section microstructure of samples after 105 cycles.The microstructures of samples after 5×10^(5) and 2×10^(6) cycles show slight difference and present a tribological transfer structure layer with thickness of about 500 nm.Additionally,the microstructure evolution enters the stable stage.

Flow-accelerated corrosion behavior of 13Cr stainless steel in a wet gas environment containing CO_2

This work investigated the flow-accelerated corrosion （FAC） behavior of 13Cr in a wet CO2-containing environment at different flowing gas velocities mid impinging mlgles, with the natural-gas pipeline environment simulated by a self-assembled impingement jet sys- tem. Surface molphology determination, electrochemical measurements, mid hydromechaziics numerical analysis were cmlied out to study the FAC behavior. The results demonstrate that pitting corrosion was the primary mode of corrosion in 13Cr stainless steel. High-flow-rate gas destroyed the passive film mid decreased the pitting potential, resulting in more serious corrosion. The corrosion degree witk various im- pact mlgles showed the following order： 90~ 〉 60~ 〉 45~. The shear force and the electrolyte from the flowing gas were concluded to be the determinm^t factors of FAC, whereas the shear force was the main factor responsible for destroying the passive film.

激光功率对316L不锈钢熔覆层组织及性能的影响

为了解决316L不锈钢激光熔覆层成形差、耐腐蚀性低的问题,采用显微组织观察、硬度实验、常温冲击及电化学测试等试验方法,对不同激光功率下熔覆单层及多层熔覆层的成形、组织及性能进行检测和分析。结果表明,随着激光功率的增大,熔覆层高度呈现先增加后减小的变化趋势,熔覆层内部析出相的含量以及稀释率则呈现上升趋势;激光功率过小易引起熔覆层开裂,过大则会引起熔覆层晶粒异常长大;随着激光功率的增加,熔覆层硬度呈增大趋势,当激光功率达到450 W时,熔覆层与基材结合界面处硬度值达到最大,为475 HV;而熔覆层的冲击性能和耐腐蚀性能则随着激光功率的增大呈现下降趋势,当激光功率为300 W时,其冲击韧性最大为92 J,且熔覆层具有最优的耐腐蚀性能,腐蚀电位E_(corr)最高为-0.3 V,且腐蚀电流密度I_(corr)最小为0.165 A/cm^(2);因此,当熔覆速率为3 mm/s、送粉速率为14 g/min、搭接率为50%时,采用300 W激光功率制备的熔覆层可得到优异的冲击和耐腐蚀性能。研究结果可为316L激光熔覆层工艺调控及性能改善提供参考。

超声冲击对钢桥焊缝耐腐蚀性能的影响

为研究超声冲击对钢桥焊缝部位耐盐雾腐蚀性能的影响,对焊缝试件进行超声冲击并进行盐雾腐蚀试验,通过金相试验分析了焊缝超声冲击后的表面微观形貌.建立焊缝盐雾腐蚀有限元模型,对比了不同冲击时间下试件的腐蚀深度、表面电位和表面电流密度.结果表明:超声冲击细化了表面晶粒尺寸,减少晶界碳化物占比,有效降低试件的腐蚀敏感性.随着超声冲击时间的增加,试件耐盐雾腐蚀性能先升高后降低.当超声冲击时间为180 s及冲击速度为3 mm^(2)/s时,试件耐盐雾腐蚀性能表现出最优.

冲击作用双点腐蚀埋地管道力学分析

受落石冲击作用的埋地管道极易造成巨大损害,严重影响管道安全运行。受环境和输送介质影响,长输管道腐蚀产生往往不以单一缺陷出现,当管道上产生两个或多个缺陷时可能导致情况更加复杂。结合国内外研究现状,采用ABAQUS软件构建环向和轴向双点腐蚀有限元模型,对管道内压、落石冲击速度、腐蚀缺陷尺寸等参数进行力学分析。研究结果表明:轴向和环向双点腐蚀应力应变变化规律曲线大致相似,轴向双点腐蚀敏感性高,更易遭受破坏失效。管道内压、缺陷深度和落石冲击速度对双点腐蚀管道影响显著,腐蚀加深极易造成管道破坏失效,腐蚀长度和腐蚀宽度对管道应力应变影响较小。对于途经崩塌区的管道,可采取增加壁厚、管道埋深和设置防护网等措施,降低管道遭受落石冲击危害,有效提升管道整体安全性。

基于超声冲击处理的多晶硅还原炉316L不锈钢焊缝消应力研究

电子级多晶硅生产设备有超洁净要求,使得超声冲击处理(Ultrasonic impact treatment,UIT)方法不适应于该类设备的消应力,因为处理导致的表面深坑、毛刺等缺陷可能挂污、藏水,降低产品纯度。鉴于此,研究UIT后打磨去除表面缺陷对引入的残余压应力的影响。结果表明,UIT能够有效将焊缝残余拉应力转变为压应力,高强度UIT和高覆盖率UIT在引入压应力上可达相近效果,打磨去除表面缺陷对残余压应力的影响不大。

基于超声冲击处理的在役反应器焊缝消应力及高温运行对应力的影响研究

鉴于多晶硅还原炉有发生应力腐蚀开裂的风险,本文应用超声冲击处理对在役还原炉进行消应力处理,并研究打磨降低粗糙度防止挂污、藏水和高温运行1个月对残余应力的影响。结果表明,超声冲击处理能有效降低在役还原炉焊缝的残余应力,使部分区域应力转为压应力,而打磨对残余应力的影响不大,但超声冲击处理后高温运行会导致应力释放,使超声冲击的有益效果降低,但整体上焊缝仍保持在较低的残余应力水平。

海洋油气管道腐蚀的影响及对策

伴随工业时代的到来,我国对于海洋资源的开发力度逐渐增强,海洋油气资源属于资源开发工作中的关键性内容,在对海洋油气资源进行开发作业时,油气集输管道在海洋中受到腐蚀的问题会对资源开发效率带来一定的影响。本文重点分析了油气管道在海洋环境下存在的常见腐蚀影响因素,主要包括海水的含盐量与导电率、海水的流动、油气混合物中存在H_(2)S和CO_(2)等伴生物,具体可通过对管道进行涂刷外防腐涂层、内防腐及阴极保护等措施来加以应对,并不断探索研究新的管道防腐技术,推动我国海洋油气资源开发应用领域的进一步发展。

1Cr13叶片钢组织和性能的研究

对1Cr13叶片钢热处理后进行了相关耐蚀性测试和微观组织分析、高温冲击韧性测试、不同温度下的持久极限等相关理化检验,以期掌握该钢作为叶片材料使用时关键物理参数,对叶片的安全运行具有积极的指导作用,同时有助于科研人员参考相关技术参数。

组合梁斜拉桥拉索重要性分析及锈蚀影响研究

组合梁斜拉桥在大跨径桥梁中应用广泛,其主梁刚度相对较弱、混凝土板容易开裂,整体受力状态受斜拉索运营状况的影响较大。为研究斜拉索锈蚀或断索对组合梁斜拉桥的影响程度,给出斜拉索的日常管养建议。依托一座大跨径钢-混组合梁斜拉桥,首先通过基于广义结构刚度的变化率指标对各斜拉索进行构件重要性分析,明确斜拉索的重要性排序关系,得出管养重点关注索区;然后通过有限元软件,模拟了依托工程在管养重点索区内斜拉索锈蚀后的力学状况,得出斜拉索逐步锈蚀劣化对桥梁结构静力效应的影响程度。研究成果为制定该类桥型相应的养护措施提供了参考。

不锈钢475℃脆及其影响分析

不锈钢在450~550℃温度范围内长时间加热,其冲击韧性会显著下降,这种现象称为475℃脆。分析475℃脆的特点及成因,介绍了几种典型不锈钢材料的475℃脆,并探究了热处理温度对其冲击韧性和耐腐蚀性的影响。另外,不锈钢475℃脆后零件易发生应力腐蚀开裂而失效。

Study on Nonlinear Coupling Wave Model for Liquid Droplet-Solid Impact

In order to investigate the material corrosion by liquid droplet solid impact, a nonlinear coupling wave model adopted to analyze the impact between the spherical liquid droplet and an elastic solid plane has been developed. Many usable results such as the dimensionless pressure in the contact plane of liquid solid and inside the liquid droplet, the equivalent stress distribution inside the solid, the effect of solid elasticity on the impact, and the locations of the maximum equivalent stress in different...

空分系统循环水水质治理的分析与应用

以白银有色集团股份有限公司铜业公司制氧车间空分系统循环水为分析对象,对补充水、循环水、挂片试验进行分析,从而判断空分循环水系统为严重结垢型水质,进一步从PH、水温、电导度、水的流速及溶解氧对腐蚀的影响和循环水水量平衡计算来分析浓缩倍数及各循环水参数。添加PF-305阻垢缓蚀剂对本公司空分循环水系统的应用。

镀层中磷含量对金刚石微粉化学镀镍品质的影响

在金刚石微粉表面化学镀镍,通过改变镀液的pH值,得到不同磷(P)含量的镀层,探究镀层中P含量对镀层形貌、耐蚀性和冲击韧性的影响。用扫描电镜观察不同P含量镀层的形貌;用质量分数为10%的盐酸浸泡腐蚀镀镍金刚石微粉,研究镀层中P含量对镀层耐蚀性的影响;用冲击韧性测试仪测试镀层中P含量对镀层冲击韧性的影响。结果表明:随镀层中P含量增加,金刚石微粉镀层表面瘤状凸起物增加,表面越来越粗糙,高磷镀层表面凸起最密集;随镀层中P含量增加,镀层腐蚀失质量逐渐降低,耐蚀性逐渐增强;随镀层中P含量增加,镀层冲击韧性逐渐变差。

含内腐蚀缺陷埋地管道冲击作用下力学分析

山体落石是西南山区造成管道失效破坏的主要地质灾害之一。伴随油气管道服役年限增加,长输管道出现腐蚀问题不可避免,落石冲击载荷和管道缺陷组合极大增加管道失效风险。根据西气东输一线相关参数,利用ABAQUS软件建立落石冲击含内腐蚀埋地管道模型。通过改变管道内压、内腐蚀缺陷尺寸、覆土埋深、管道壁厚等对管道响应动力进行探讨。结果表明:埋地管道应力受缺陷长度、缺陷宽度影响较小;管道内压、缺陷深度和落石冲击速度对管道有较大影响,其中缺陷加深更易造成管道临界失效;增加覆土埋深和管道壁厚等措施能有效提升整体管道安全性,仍需考虑覆土深度和管道耗材对投资维护成本影响。

环氧乙烯基酯树脂/玻璃鳞片复合材料冲击韧性的影响因素

研究了树脂性能及含量、玻璃鳞片形状、球形填料以及表面活性剂等因素对树脂基玻璃鳞片复合材料的冲击韧性影响。发现树脂增韧以及含量增加可显著提升复合材料的冲击韧性;减小玻璃鳞片片径虽可有效提升材料冲击韧性,但会导致材料水蒸气渗透量增加,因此鳞片片径不宜小于0.4 mm;白炭黑含量在1.5 wt%时冲击韧性达到峰值;偶联剂含量不高于1 wt%时,冲击韧性随偶联剂含量提高而增长。

Corrosion and impact-abrasion-corrosion behaviors of quenching- tempering martensitic Fe-Cr alloy steels

The corrosion and impact-abrasion-corrosion behaviors of quenching-tempering Fe-Cr martensitic steels for ball mill liner were investigated in the corrosive slurry of a copper mine compared with high manganese steel.It is found that the corrosion resistance and the protectiveness of the passive film of Fe-Cr martensitic steels became worse when the carbon content increased.The quenching-tempering Fe-Cr martensitic steel showed better impact-abrasion-corrosion resistance in the corrosive slurry compared with the high manganese steel,especially the alloy steel with the carbon content of 0.3 wt.%.The synergistic effect between mechanics and corrosion has also been analyzed to further reveal the impact-abrasion-corrosion mechanism of the steels.The damage from pure mechanics accounted for the largest percentage(over 65%)for all steels,demonstrating that mechanical damage played the most important role in the impact-abrasion-corrosion behaviors of the steels.The impact and cracking resistance of the steel should also be paid special attention during the development of new materials for ball mill liner.

Effects of Modified Inclusions and Precipitates Alloyed by Rare Earth Element on Corrosion and Impact Properties in Low Alloy Steel

This study has focused on the morphology and distribution of inclusions and precipitates modified by rare earth(RE)elements,which has a decisive influence on microstructure,corrosion properties and impact behaviors in Q355 low alloy steel.Characterized by the method of electrolytic extraction and ASPEX-scanning electron microscopy(ASPEX-SEM),small-sized spherical RE inclusions have been modified to replace elongated MnS and large-sized Al_(2)O_(3).Q355RE steel after RE alloying has lower corrosion rate and higher value ofα/γ,due to the formation of stable and dense rust layers.Q355RE steel also exhibits better resistance to fracture at low temperature,owing to the presence of RE modification to inclusions and its effects on reducing crack initiation and propagation.Nano-scale RE precipitates containing sulfur and phosphorus is observed along grain boundaries by transmission electron microscopy(TEM).The purification of grain boundaries by RE is beneficial to the improvement of corrosion and impact properties.