激光重熔高速电弧喷涂FeNiCrAl涂层的工艺优化

以外观形貌、孔隙率和显微硬度为评价指标,利用正交试验并结合极差分析法考察了激光功率、扫描速率和搭接步距这3个激光重熔工艺参数对高速电弧喷涂FeNiCrAl涂层重熔层的影响,得到优化工艺参数为:激光功率1 700 W,扫描速率10mm/s,搭接步距2.1 mm。结果表明,影响激光重熔最主要的参数是激光功率,随着激光功率的增大,重熔层的孔隙率先增大后减小,显微硬度显著增加。优化后所制重熔层的孔隙率为0.9%,显微硬度567.03 HV_(0.1),比喷涂层的显微硬度提高38.5%。重熔后,喷涂层的层状堆叠结构消失,产生了树枝晶和枝晶间组织。     

等离子物理气相沉积高熵合金涂层及组织性能

采用等离子物理气相沉积的方法在316L不锈钢表面制备了AlCoCrFeNi高熵合金涂层,研究了喷涂距离和电流对高熵合金涂层物相组成、表面形貌、截面形貌、硬度、结合强度和耐磨性的影响。结果表明,不同喷涂距离和电流下,高熵合金涂层都主要由BCC、B2和FCC相组成;随着电流或者喷涂距离增加,涂层中BCC平均晶粒尺寸先增后减。当喷涂距离为460 mm时,随着电流从1600 A增加至2000 A,涂层平均摩擦系数逐渐增大,表面和截面硬度先减后增,涂层结合力和结合强度先增大后减小,涂层的磨损率先增加后减小;当电流为1800 A时,随着喷涂距离从420 mm增加至500 mm,涂层平均摩擦系数逐渐减小,表面硬度先减后增,截面硬度先增后减,涂层结合力和结合强度逐渐增大,涂层的磨损率逐渐减小。高熵合金涂层的磨损率与涂层表面硬度和内聚强度都有一定相关性。     

聚苯乙烯粉选择性激光烧结工艺参数优化

对聚苯乙烯(PS)粉在激光功率20 W、预热温度70℃、扫描间隔0.30 mm等工艺参数下,研究了扫描速度和层厚对烧结试样长度、宽度、高度相对误差及孔隙率等的影响,并在电镜下观察了烧结试样微观组织,对工艺参数进行优化。结果表明:PS粉烧结时,在不同工艺参数下会分为熔融区和微熔区,熔融区和微熔区烧结件长和宽均由于收缩变形而小于理论值;在熔融区,随着扫描速度和层厚的增大,长、宽尺寸精度越来越高;在微熔区,长、宽尺寸精度变化不大,同时试样由过深烧结到烧结不足,高度值由大变小,试样孔隙率逐渐增大。扫描速度对孔隙率影响较大,分层厚度对孔隙率影响较小,确定层厚在0.20~0.22 mm、扫描速度在2 100 mm/s为最佳烧结工艺参数。     

天线罩表面导电涂层的制备工艺及性能研究

为解决由碳纤维复合材料制备的雷达天线罩自身导电性能差、反射能力弱和空间防护能力不高的问题，先通过电弧喷涂技术在Q235钢模具表面制备铝涂层，然后在碳纤维复合材料固化的过程中将其转移至天线罩表面。研究了电弧喷涂时的主要工艺参数对铝涂层孔隙率的影响，得到最佳的工艺参数为：空气压力0.6 MPa，喷涂距离300 mm，喷涂电压28 V。扫描电镜表征和热淬法测试表明，通过上述方法在天线罩表面制备的导电涂层均匀连续，表面致密，无裂纹、空腔和外来夹杂物，结合力良好。     

LW3-1导管架腿乙二醇储罐热喷铝工艺

讨论了LW3-1导管架腿贫乙二醇(MEG)储罐热喷铝工艺表面处理要求和影响热喷铝质量的因素,总结了施工过程中出现的质量问题,包括焊缝处起皮、环板涂层脱落、附着力未达要求等,提出了相应的解决方案:增加环板焊缝打磨和内部缺陷打磨工艺,以消除钝化层和表面缺陷的影响;采用16#氧化铝喷砂增大表面粗糙度;采用大功率通风机减少施工过程中粉尘的影响;改变喷涂方式,加强设备检查和工人培训等。通过采取以上措施,有效地提高了热喷铝的质量。MEG罐热喷铝涂层厚度在180~300μm之间,附着力单点测试值在7 MPa以上,平均值在9 MPa以上。     

钢结构高膜厚热喷锌施工工艺研究

研究了热喷锌送丝电压(送丝速率)、喷涂电流和锌丝直径对厚度达到200μm左右的热喷锌涂层品质的影响。当送丝电压为20 V,喷涂电流为200 A时,涂层外观成型良好,附着力可达8.4 MPa,且能耗较低。当锌丝直径为2.0 mm时,锌丝损耗率比采用锌丝直径为1.6 mm和3.0 mm时分别低67%和35%。该施工工艺简单、品质可控,具有良好的经济效益,在工程中获得了良好的应用和验证。     

泡沫铝发泡效率与泡体均匀性研究

研究了用TiH2作为发泡剂制备泡沫铝过程中发泡剂加入量、发泡温度、搅拌时间、搅拌速度和保温时间对泡沫铝孔隙率、发泡效率和结构均匀性的影响。研究结果表明,随着发泡剂加入量的增加,泡沫铝的孔隙率逐渐上升;随着发泡温度的升高,发泡效率和均匀度逐渐减小;随着保温时间的增加,泡沫铝样品的孔隙率上升、发泡效率降低、均匀度减小;在5个因素中,搅拌时间和搅拌速度属于次要因素。当发泡剂的加入量为1.1%～1.3%、发泡温度在620～640℃之间、搅拌时间2.5～5.0 m in、搅拌速度1 500～2 500 rpm和保温时间3.0～5.0 m in时可以制备出孔隙率75%～85%、发泡效率80%以上、均匀性80以上、平均孔径1～4 mm的泡沫铝样品。     

采用等离子转移弧表面处理技术制备铝复合喷焊层

对用等离子转移弧表面呀焊铝复合喷焊层工艺进行了研究,对等离子喷焊,工艺参数和中物各种成分进行试验优选,同时对喷涂层的各种性能进行了测定。指出这种铝复合涂层具有很高的强度和耐蚀性,是很有希望的复合涂层。     

正交试验法优化聚酰亚胺表面喷涂有机硅涂层的工艺参数

为了实现太阳能电池基板对原子氧的防护功能,以涂层表观形貌、最低厚度和厚度一致性作为质量评价指标,通过正交试验考察了几个主要的喷涂工艺参数对在聚酰亚胺表面制备有机硅涂层的影响。结果表明,喷嘴运行速率越快,涂层越薄;行间距越小,涂层厚度越均匀;空气压力越高,涂层表观形貌越好,但厚度一致性越差。经过第二次正交试验验证,得出优化的工艺参数为:喷嘴运行速率70～130 mm/s,雾化压力0.36～0.54 MPa,空气压力0.24～0.33 MPa,喷涂距离140～200 mm,行间距18～21 mm。在上述条件下可制得厚度为40～140μm的合格涂层。     

电弧喷涂工艺参数对套管壁铝涂层性能的影响

采用电弧喷涂的方法,在N80套管壁喷涂铝涂层。使用电子万能试验机测试并计算涂层与基体的结合强度,采用称重法测定涂层孔隙率的方法,研究了试件表面粗糙度、喷涂电压和喷涂距离对涂层性能的影响。研究结果表明:试件表面粗糙度在55~65μm之间,喷涂电压34V,喷涂距离160mm,空气压力0.5MPa,喷涂电流120A,可获得性能较为理想的铝涂层。     

钢结构棱角处理及其电弧喷铝涂层结合力试验

钢结构棱角在防腐涂装过程中存在应力集中现象,显著降低了涂层结合力,导致整个防护体系从边角处被腐蚀介质快速突破,从而大大缩减腐蚀防护体系的保护寿命。本试验设计了3种打磨棱角的圆角半径,进行了电弧喷铝涂层的附着力测试。研究结果表明,钢结构棱角打磨成R1.5mm圆角后,即可保证热喷铝涂层的附着力达到国标要求;施工时采用R2.0mm圆角,可彻底解决边角涂层的结合力问题。     

Critical parameters to determine mean bubble size of generated foams from a foam generator

The filtration performance of filter media fabricated by foam coating technology is highly dependent upon their pore sizes. Therefore, we investigated the effect of the mixing ratio of combined coating components (PTFE emulsion, a foam stabilizer, a foaming agent, and a thickener) and operating parameters (feed rate of coating solution, air flow rate, mixing speed, and cooling temperature) on the bubble size distribution of generated foams in a foam generator. The mean bubble size and bubble size distributions were observed through microscopic observations with an optical microscope. We found that viscosity was the most critical parameter in preparing a coating solution, and the entire series of operating parameters as mentioned above influenced the bubble size in a foamed solution. The bubble size decreased with an increasing ratio of thickening agent up to 1.8%, mixing speed, and with decreasing solution feed rate, and cooling temperature. Furthermore, we had a minimum bubble size for the condition of air flow rate at 200 mL/min. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2062–2067, 2013     

铝粉的质量分数对达克罗涂层耐蚀性的影响

以片状锌粉和片状铝粉为原材料制备不同铝的质量分数的达克罗涂层.通过盐雾试验和电化学方法评价涂层的耐蚀性.结果表明:随着铝的质量分数的增加,达克罗涂层逐渐变得光亮、细致、光滑;涂层的自腐蚀电位依次升高,铝的质量分数50%以上的涂层,不具备牺牲阳极性能;涂层耐盐雾腐蚀时间的变化趋势与涂层牺牲阳极作用持续时间的变化趋势一致,均先升后降,在铝的质量分数为15%处达到极大值.     

化学镀镍316不锈钢激光焊接裂纹研究

通过调整镀液中磷酸钠的质量浓度,在316不锈钢表面化学镀得到P质量分数分别为1.2％、2.3％和3.4％的镍镀层.对镀镍316不锈钢进行激光焊接实验,得到较佳的工艺参数为:激光功率50 W,脉冲宽度60 ns,焊接速率200 mm/s.当镀层中磷的质量分数为1.2％时,焊缝中无裂纹,剪切强度为242 MPa.随镀层中磷...     

Numerical simulation and combination optimization of aluminum holding furnace linings based on simulated annealing☆

To reduce heat loss and save cost, a combination decision model of reverb aluminum holding furnace linings in aluminum casting industry was established based on economic thickness method, and was resolved using sim-ulated annealing. Meanwhile, a three-dimensional mathematical model of aluminum holding furnace linings was developed and integrated with user-defined heat load distribution regime model. The optimal combination was as follows:side wal with 80 mm alumino-silicate fiber felts, 232 mm diatomite brick and 116 mm chamotte brick;top wall with 50 mm clay castables, 110 mm alumino-silicate fiber felts and 200 mm refractory concrete;and bottom wal with 232 mm high-alumina brick, 60 mm clay castables and 68 mm diatomite brick. Lining tem-perature from high to low was successively bottom wal , side wal , and top wall. Lining temperature gradient in increasing order of magnitude was refractory layer and insulation layer. It was indicated that the results of com-bination optimization of aluminum holding furnace linings were valid and feasible, and its thermo-physical mechanism and cost characteristics were reasonably revealed.     

陶瓷膜净化溶剂油的实验研究

研究了平均孔径0.2 mm的陶瓷膜对含杂质溶剂油的微滤过程,选用不加水和加0.5%(w)水2种料液,考察了操作时间、跨膜压差、错流速度、温度和铝粉含量对膜通量及铝粉截留率的影响,研究了反冲操作、浓缩和污染膜清洗过程. 结果表明,不加水较加水料液的膜通量明显增大;随操作时间延长,膜通量下降至稳定,铝粉截留率迅速增大至100%;跨膜压差增大或温度升高使稳定通量增大;错流速度增大,稳定通量先升高之后不变;铝粉含量越高,膜通量越低. 适宜的操作参数为跨膜压差0.16 MPa、错流流速3.9 m/s和温度40℃. 反冲操作能有效提高膜通量;浓缩过程中膜通量快速下降至平缓阶段再较快降低,净化溶剂油澄清透明;采用0.15%(w)洗洁精和0.25%(w)硝酸清洗可使通量恢复到新膜通量的94.9%.     

Effect of Acid on the Coating of Boehmite onto Silicon Carbide Particles in Aqueous Suspensions

It is shown that the addition of acid in aluminum alkoxide precursor gels is critical to the success of coating aluminum oxide onto SiC particles. For aluminum sec -butoxide processed at 90°C, the addition of acid dissolves the gel network and facilitates the coating of aluminum oxide on SiC. On the other hand, when the coating is performed at room temperature, even with the addition of acids, coating of aluminum oxide is not successful.     

电流密度对无机熔盐法制备钢基镀铝层形貌特征的影响

以1070工业纯铝为阳极,Q235钢为阴极,置于AlCl3-NaCl-KCl三元无机熔盐中,150℃下电镀处理,获得了完整、均匀的镀层。并且研究了电流密度对镀层形貌的影响。经SEM和EDS分析表明,镀层主要成分是金属铝颗粒。SEM分析表明,在一定电镀时间下,随着电流密度的提高,膜层颗粒由粗大的树干状晶粒转变为不规则块状晶粒;当电流密度进一步增大时,膜层颗粒逐渐形成细小的球状晶粒。晶粒尺寸随着电流密度的提高而逐渐减小。     

Electrolytic deposition of Ni-Co-Al2O3 composite coating on pipe steel for corrosion/erosion resistance in oil sand slurry

To improve the resistance of the hydrotransport pipe steel to corrosion and erosion in oil sand slurry, a Ni-Co-Al₂O₃ composite coating was fabricated by electrolytic deposition on X-65 pipe steel substrate. Potentiodynamic polarization curve and electrochemical impedance measurements show that the deposited coating significantly improves the corrosion resistance of the steel in water-oil-sand solution that simulates the chemistry of oil sand slurry. The corrosion resistance of the coating increases with the increasing Al₂O₃ particle concentration in electrolyte, cathodic current density, electrode rotating speed and temperature. However, a maximum value of corrosion resistance as a function of the depositing parameters is observed, indicating that the optimal electrodepositing parameters and operating conditions are essential to the maximization of the corrosion resistance of the coated steel in oil sand slurry. The optimal depositing conditions are suggested in the given system. The morphology, structure and composition of the coatings were characterized by scanning electron microscopy and energy-dispersive X-ray analysis. The Ni-Co-Al₂O₃ composite coating develops a compact, uniform, nodular structure with an average thickness of 50-200 microns. The Al₂O₃ amount in the coating increases with the increasing Al₂O₃ concentration in electrolyte, which also enhances the co-deposition of Ni and Co. The micro-hardness and wear resistance of the composite coatings are much higher than the steel substrate and increase with the increasing Al₂O₃ particle amount in the coating.     

Influence of V-containing species on formation and corrosion resistance of PEO coatings developed on AZ31B Mg alloy

The defects, micropores, and microcracks on the plasma electrolytic oxidation (PEO) coating severely affect the long-term anti-corrosion feature. Inclusion of additives in the electrolyte is a feasible and effective strategy to attain the more intact PEO coating. The PEO coatings are fabricated on AZ31B Mg alloys in an silicon-based electrolyte with Na₃VO₄ (OPEO), NaVO₃ (MPEO), and V₂O₃ (VPEO), respectively, to explore the influence of additives on the corrosion resistance. MPEO sample has the smallest poriness and pore size unfolding the best anti-corrosion resistance, which is also consistent with the electrochemical analysis. Even after 336 h salt spray test, the MPEO coating exhibits the least corrosion. The excellent anti-corrosion performance of MPEO sample is the synergistic effect of inorganic salts and multiple metal oxides generated in the formation of PEO coating. Inclusion of inorganic salt with valence change metal is a feasible pathway to achieve the compact PEO coating since multiple metal oxides could be produced and deposited in the PEO coating during the fabrication.