共查询到20条相似文献,搜索用时 187 毫秒
1.
湿法超声机械镀锌-铝层的结构分析 总被引:1,自引:0,他引:1
提出了湿法超声机械镀Zn-Al复合镀层的工艺,采用湿法超声机械镀设备制备了Zn-Al复合镀层。采用金相显微镜、白光干涉仪、多功能扫描电子显微镜及其配备的能谱分析仪观察分析了镀层的结构形貌和镀层的化学成分。结果表明,在工件表面获得了一定厚度的锌-铝层,镀层主要由Zn、少量的Al、Sn和Fe构成,锌粉颗粒是镀层的主体,片状铝粉在镀层中分布不均匀;镀层表面细腻、均匀、平整,但镀层中铝的含量比施镀前混粉中铝的含量低。 相似文献
2.
以Q235钢片为基体,采用湿法超声机械镀制备Zn–Al复合镀层。用扫描电子显微镜及其配备的能谱仪分析了锌–铝复合镀层的表面形貌、断面形貌和元素组成,并用测厚仪、贴滤纸法和划格试验分别对镀层的厚度、孔隙率和结合力进行表征。结果表明,湿法超声机械镀Zn–Al复合镀层是由锌粉和铝粉颗粒相互镶嵌、填充所形成的致密堆积体,表面均匀、平整,与基体的结合强度高。镀层主要由锌、铝、锡和铁组成,铝的质量分数低于施镀前混合粉体中铝粉的质量分数。在考虑施镀过程中金属粉的损耗后,所得Zn–Al镀层的厚度满足预定的厚度(30μm)要求。 相似文献
3.
4.
5.
6.
7.
8.
以有效增强汽车用钢板的耐蚀性为目标,开展试验研究。采用喷溅盐雾腐蚀法,在相同条件下分别考察了纯质钢板、镀锌钢板和镀锌-铝钢板的耐蚀性。结果表明:镀锌-铝钢板的腐蚀程度较轻,腐蚀速率较低。因铝粉的掺入影响了镀层的腐蚀进程,因而赋予镀锌-铝钢板较好的耐蚀性。 相似文献
9.
为了改善铝粉在CL-20基含铝炸药中的反应动力学特性,利用溶剂-非溶剂法制备了CL-20/Al复合颗粒,实现了CL-20与Al在微结构上的紧密结合,通过直接法制备了由CL-20/Al复合颗粒构成的组分质量分数为85%CL-20/10%Al/5%黏结剂的含铝炸药,并与常规法制备的相同组成的CL-20基含铝炸药进行了机械感度、爆热、爆炸罐试验和圆筒试验等结果的对比。结果表明,CL-20/Al复合颗粒会使含铝炸药的撞击感度略有提高,而摩擦感度不变,但总体上对机械感度影响不大;通过CL-20/Al在微结构上的复合,缩短了Al粉与爆轰产物之间的扩散距离,可以显著改善Al粉的反应动力学性能,提高Al粉在含铝炸药爆炸过程中的反应完全性,促使部分Al粉在爆轰区内参与反应,相比于常规法制备的相同组成的含铝炸药,可使含铝炸药的爆热从6787J/g提高至6930J/g,爆炸罐内爆炸场最高温度从544.3℃提高至661.2℃,格尼系数由2.88mm/μs提高至3.10mm/μs。 相似文献
10.
11.
为防止铝粉在存储中氧化失活,同时为含铝炸药配方设计提供借鉴,采用聚叠氮缩水甘油醚(GAP)对不同尺寸Al粉(平均粒径分别为50nm和1~2μm)进行包覆改性,获得Al@GAP复合粒子;采用扫描电镜(SEM)、透射电镜(TEM)表征其形貌;用差示扫描量热法(DSC)对不同质量比的(Al@GAP)/LLM-105混合体系的热分解过程进行了研究。结果表明,采用两步包覆法获得了不同尺寸Al粉表面包覆GAP的核壳结构复合粒子;相较于包覆前的微米级Al粉,加入GAP包覆的纳米Al粉后混合体系的热分解峰温明显降低;当Al粉质量分数大于10%时,GAP包覆后的(Al@GAP)/LLM-105混合体系的熵变(ΔS~≠)和焓变(ΔH~≠)较Al/LLM-105混合体系有所减小;(Al@GAP)/LLM-105混合体系的活化能、热爆炸临界温度及热力学参数ΔS~≠和ΔH~≠随纳米Al粉含量的增加而降低,当Al粉质量分数为30%时,较LLM-105分别降低4kJ/mol、3℃、4.3J/(mol·K)、4.2kJ/mol。 相似文献
12.
微米铝粉在声场中的振荡燃烧特性 总被引:2,自引:0,他引:2
为了解声场中铝粉的燃烧特性,建立了甲烷平面燃烧器,利用外置喇叭产生振荡,进行了微米级铝粉的燃烧实验。研究了铝粉在不同振荡频率下的分布燃烧响应特性及粒径分别为10、20、30μm的3种铝粉颗粒的燃烧特性和产物的阻尼特性。结果表明,振荡频率不同时,铝粉燃烧对振荡压强的增益作用不同,粒径为20μm铝粉燃烧,在振荡频率200Hz和300Hz时增益作用明显。铝粉粒度越大,分布燃烧增益越大。粒径为10μm铝粉对燃烧器高频振荡阻尼最大。随着铝粉粒度增加,燃烧产物颗粒对高频压强振荡的阻尼减小。 相似文献
13.
PDA包覆铝粉及其在HTPB中的分散稳定性 总被引:1,自引:0,他引:1
通过原位多巴胺(DA)聚合法在铝粉表面包覆聚多巴胺(PDA),制备了Al@PDA复合颗粒;采用SEM表征不同DA质量浓度下Al@PDA的表面形貌。用XRD测试铝粉包覆前后的晶型;采用XPS分析Al@PDA的表面元素组成;通过沉降法研究了铝粉和Al@PDA在HTPB中的分散稳定性;通过制备固化胶并切片取样观察固体颗粒在HTPB中的分散情况。结果表明,当DA质量浓度为3.5g/L时对铝粉的包覆效果最好,在铝粉表面形成牢固的PDA薄膜;包覆前后Al的晶型没有改变;XPS在Al@PDA表面检测到的C-OH、C=O组分和π-π共轭结构证实了PDA包覆层的存在。沉降24h后Al-HTPB体系出现分层,而Al@PDA-HTPB体系仍然颜色均一,表明Al@PDA在HTPB中的分散稳定性明显优于原料铝粉。 相似文献
14.
A. P. Il'in A. A. Gromov D. V. Tikhonov G. V. Yablunovskii M. A. Il'in 《Combustion, Explosion, and Shock Waves》2002,38(1):123-139
The paper studies properties of an ultrafine aluminum powder produced by electric explosions of conductors, whose particles are stabilized by coating with aluminum diboride immediately during the synthesis of the powder. The ultrafine aluminum powder stabilized in such a manner has special properties: narrow particle size distribution, increased dispersity, and higher resistance to oxidation upon heating. 相似文献
15.
The effect of surface modification of aluminum powder on its flowability, combustion and reactivity 总被引:1,自引:0,他引:1
Surface modification of aluminum powders for the purpose of flow improvement was performed and several samples were prepared. Correlations between the flowability and reactivity for these powders as well as for the initial untreated aluminum powder were established. The powders were characterized using Scanning Electron Microscope (SEM), particle size distribution, angle of repose flowability test, Constant Volume Explosion (CVE) combustion test, and Thermo-Gravimetric Analysis (TGA). The surface modification of micron-sized aluminum powders was done by: (1) dry coating nano-particles of silica, titania and carbon black onto the surface of spherical aluminum powders and (2) chemically and physically altering the surface properties of the same powders with methyltrichlorosilane. All surface modifications improved flowability of the powders. CVE measurements indicate that powders with an improved flowability exhibit improved combustion characteristics if the powder treatment does not add an inert component to aluminum. The TGA results do not show significant differences in the reactivity of various powders. Based on combined flowability and CVE characteristics, the silane modified material gave the best results followed by the powders dry coated with carbon, titania and silica, respectively. 相似文献
16.
Xiangbo Meng 《Powder Technology》2009,195(3):264-45
This experimental study investigated particle size evolution in deposited layers during typical electrostatic powder coating processes, using two powder (coarse and ultrafine) systems. Results disclosed that powder coating is a size-selective process in which the motions of in-flight particles are size-dependent. As a result, particles deposited on different regions of the substrate present some size discrepancy which accounts for a size-decreasing tendency along radial direction for both powders. In comparison with coarse powder, however, ultrafine powder can greatly alleviate the size discrepancy. Furthermore, it was also revealed that, due to the size-selective effect, locally deposited particles are with narrower size distributions than the original particles. The study still demonstrated that small particles are more prone to adhere on the substrate in coarse powder coating processes while large particles take the priority to deposit in ultrafine powder coating processes, due to different dominant factors. However, because of the intensifying back corona, the deposited particles show a size-decreasing tendency with extended spraying duration, which is commonly exhibited in both coarse and ultrafine powder coating processes. Nevertheless, in this study it was also found that charging voltage plays a limited influence on the size evolution. 相似文献
17.
《Ceramics International》2023,49(2):2157-2166
Plasma spray physical vapor deposition (PS-PVD) is a technology that combines the advantages of traditional atmospheric plasma spraying (APS) and electron beam physical vapor deposition (EB-PVD). As the feedstock of the PS-PVD, nano-agglomerated powder is critical on determining the microstructure of the obtained coating. In this study, a method to characterize the cohesion of nano-agglomerated powders was investigated. The nano-agglomerated powders fractured into smaller particles under ultrasonic waves. Their particle size distributions were measured to quantitatively compare their cohesiveness. The change rate in the percentage of powders with particle size less than 5 μm was selected as the value for the cohesion comparison. A high change rate corresponded to a faster fracture and lower powder cohesion. Furthermore, the fracture behavior and heat and mass transfer process of nano-agglomerated powders in the plasma torch were studied by combining 3-D simulation and observation of the microstructures of PS-PVD coatings sprayed with different powders. To obtain a quasi-columnar coating, the nano-agglomerated powder required high cohesion. Finally, a suitable powder was selected and quasi-columnar structure coatings were obtained by optimizing the PS-PVD parameters. 相似文献
18.
Ljubica Andjelković Marija Šuljagić Mladen Lakić Dejan Jeremić Predrag Vulić Aleksandar S. Nikolić 《Ceramics International》2018,44(12):14163-14168
Zinc–ferrite, nickel–ferrite and mixed nickel–zinc ferrites were successfully synthesized via the thermal decomposition method from acetylacetonate complexes. To control the particle size and enhance dispersibility in an aqueous medium, starch, a natural and biocompatible compound, was used for the first time for coating such magnetic powders. X-ray powder diffraction (XRPD) was performed to study the structural properties of all samples. The presence of a single-phase spinel structure as well as the cation distribution in both sites of all investigated magnetic powders was confirmed. The values of unit cell parameters obtained from the results of the Rietveld analysis decreased, while the average crystallite size increased with increasing Ni2+ content. The average microstrain parameters unambiguously showed a change in the spinel structure with cation distribution. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) analyses were also utilized to characterize the synthesized materials, corroborating the XRPD data. The obtained results indicated that functionalization by starch was successfully achieved. 相似文献
19.
20.
《Drying Technology》2012,30(15):1714-1719
The polymer-coated inclusion complex powder formation of D-limonene and β-cyclodextrin obtained by spray drying was investigated with respect to the effects of various types of polymer coating agents on the powder particle size and morphology. The addition of the polymer coating agent affected the average particle size, morphology, and internal structures of the spray-dried powders. The average particle diameter of the uncoated spray-dried powders was approximately 5 µm. The powder particle size increased upon the addition of a polymer coating reagent. With the addition of 9 wt% of the polymer coating agent, an average diameter of approximately 80 µm was obtained for the spray-dried powder particles. However, further addition showed a negligible effect on the particle size. Inclusion complex crystals were observed on the surface and inside of the powder particles. 相似文献