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1.
V. S. Zenkov 《Powder Metallurgy and Metal Ceramics》2006,45(5-6):279-282
Kinetic features of adsorption-desorption processes for a nitrogen and oxygen mixture of gases, nitrogen and water vapor at
the surface of finely-dispersed amorphous powders of brown and black boron used to synthesize metal borides are studied. The
different adsorption-chemical activity of amorphous brown and black boron powders towards the main components of an air atmosphere
is determined. It is shown that the original boron, apart from hard impurity compounds, may carry at the surface gaseous constituents
with a capacity to change the physicochemical parameters of the system in the reaction zone, and to affect the phase composition
and quality of the product obtained.
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Translated from Poroshkovaya Metallurgiya, Nos. 5–6(449), pp. 79–84, May–June, 2006. 相似文献
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Hydrogen storage properties of 2LiNH2-MgH2 system were improved by adding lanthanum hydride (LaH3), and the role of LaH3 in hydrogen sorption process of Li-Mg-N-H system was investigated. Temperature programmed sorption results showed that the addition of lanthanum hydride reduced the dehydriding/hydriding onset temperature of 2LiNH2-MgH2 system by at least 15 K. Moreover, A 0.053 wt.%/min average rate was determined for the hydrogen desorption of 2LiNH2-MgH2-0.05LaH3 composite, while it was only 0.035 wt.%/min for 2LiNH2-MgH2 system. Hydrogen absorption capacity increased from 1.62 wt.% to 2.12 wt.% within 200 min by adding LaH3 into 2LiNH2-MgH2 system at 383 K. In the dehydrogenation of 2LiNH2-MgH2-0.05LaH3 composite, LaH2 transferred to LaN phase, which reversed to LaH2 in the following hydrogen adsorption process. The reversible reaction of LaH2 ef- fectively promoted the hydrogen sorption of Li-Mg-N-H system. Moreover, the homogenous distribution of fine La hydride was fa- vorable to improving effect of lanthanum hydride. 相似文献
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O. N. Grigor’ev T. V. Dubovik N. D. Bega V. A. Kotenko V. M. Panashenko V. I. Lyashenko A. A. Rogozinskaya L. I. Chernenko 《Powder Metallurgy and Metal Ceramics》2007,46(1-2):46-50
The formation of BN-B4C composite materials by sintering in nitrogen is investigated. Structural, mechanical, and chemical characteristics of these
materials are examined. Excellent dielectric properties, thermal and chemical stability, and erosion resistance in high-intensity
laser beams enable high-temperature application of BN-B4C composite materials.
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Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 1–2(453), pp. 58–63, 2007. 相似文献
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L. R. Vishnyakov A. V. Maznaya L. N. Pereselentseva B. N. Sinaiskii 《Powder Metallurgy and Metal Ceramics》2006,45(5-6):239-243
The structure and physicomechanical properties of composite materials based on boron nitride within which new phases (mullite
and sialon) form during hot compaction are studied. It is established that the microstructure of composites is specified by
their texture formation caused by the crystal morphology of boron nitride particles and it is almost independent of composite
phase composition. It is shown that the main factor that affects strength is porosity. The dependence of strength on porosity
is exponential in character. The strength of boron nitride-mullite and boron nitride-sialon composites is 110–140 MPa and
at 20–1200°C it is almost unchanged.
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Translated from Poroshkovaya Metallurgiya, Nos. 5–6(449), pp. 33–39, May–June, 2006. 相似文献
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本文采用闭环气流磨系统对氢化后得到的粗颗粒氢化钛粉进行粉碎,利用扫描电子显微镜和粒度分析技术对结果进行表征,并对闭环气流磨的粉碎机理进行了讨论。结果表明,对粗颗粒氢化钛粉进行闭环气流磨粉碎,克服了氢化脱氢法(hydrogenation dehydrogenation,HDH)制备的钛粉存在的粒度不均匀、粒度分布较宽等品质问题;其粉碎机理可总结为,经多股高速高压氩气流冲击、打磨,粉末颗粒自身相互碰撞、摩擦,以及粉末颗粒与磨料腔腔壁、分级轮的碰撞,粗颗粒氢化钛粉从大颗粒粉碎成细小颗粒。 相似文献
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通过DSC/TG的热分析试验,研究氢化钛升温过程中分解的动力学规律,利用Coast-Redfern积分法计算了分解过程的动力学参数。结果表明,氢化钛热分解的开始温度为510℃,分解过程中总质量损耗率达3.15%,其中565~660℃温度范围内的质量损耗率占总质量损失的50%左右,分解过程中生成了比氢化钛热稳定性更高的TiHx(0.7相似文献
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氢化钛氧化处理及其热分解行为 总被引:1,自引:0,他引:1
在大气条件下进行氢化钛的氧化处理试验,利用扫描电镜和X射线衍射仪研究氧化处理后氢化钛的形貌与相组成,通过TG/DSC热分析,研究氧化处理对氢化钛热分解行为的影响规律。结果表明,氧化处理后氢化钛颗粒形貌无明显变化,随温度升高和时间延长,其颜色经历了灰黑色—蓝色—浅灰色的转变,且颗粒表面形成了Ti3O和TiO2的氧化物薄膜。与此同时,随氧化处理温度升高和时间延长,氢化钛热分解的质量损失率降低,但氢化钛的热分解温度显著提高,以AlSi12合金为基体,应用粉末冶金法制备泡沫铝,其氢化钛的氧化处理工艺为480℃/1h。 相似文献
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二氧化钛中砷的检测方法中,样品前处理多数采用硝酸-盐酸-氢氟酸混酸体系溶解,而采用此法处理样品,会存在钛容易水解且消解时间较长的问题。实验提出了硫酸-硫酸铵体系溶解二氧化钛样品的方法,不仅解决了上述问题且反应温和,并据此建立了氢化物发生-原子荧光光谱法(HG-AFS)测定二氧化钛样品中砷的方法。实验表明,砷的质量浓度在0.50~20 μg/L范围内与其对应的吸光度呈线性关系,线性相关系数为0.999 8,方法检出限为0.05 μg/L。干扰试验表明,基体钛样品中的共存元素均不干扰测定。方法用于二氧化钛实际样品分析,测定结果与电感耦合等离子体质谱法(ICP-MS)相符,相对标准偏差(RSD,n=11)小于5%,加标回收率为95%~101%。 相似文献
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研究了低碳铝镇静钢08Al中单独添加硼、钛和同时添加硼、钛对其组织和力学性能的影响,结果显示,在相同控轧控冷工艺条件下,单独添加微量硼对盘条的屈服强度和抗拉强度影响不大,单独添加质量分数0.057%的钛可使盘条屈服强度和抗拉强度升高约20 MPa,同时添加质量分数为0.004 8%的硼和质量分数为0.07%的钛可使盘条屈服强度和抗拉强度显著提高,试验中,屈服强度由260升高到316 MPa,提高了56 MPa,抗拉强度由363升高到463 MPa,提高了100 MPa。同时添加硼和钛使强度提高的原因主要是由于获得了具有高位错密度的不规则的准多边形铁素体,同时细片层珠光体相变强化对该钢强度的升高也有一定贡献。 相似文献
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硼与变色酸可形成强荧光络合物,采用分子荧光法对硼泥中硼的总量进行测定。在此基础上,选用不同的溶剂,通过连续浸取方法对硼泥中硼的分布及形态进行分析。结果表明:在λex\λem=313/380 nm,硼量在10~250 ng/25 mL范围内呈良好线性关系。硼泥中总硼含量为4.01 g/kg;各形态硼含量(w/%)依次为:水溶态(49.13)>醋酸溶解态(16.46)>螯合态(14.96)>盐溶态(3.34)>盐酸羟胺溶解态(1.00)>残渣态(0.50),测定结果对硼泥的综合治理及资源再生有一定指导意义。 相似文献
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采用氢氧化钠溶解样品,硝酸酸化,电感耦合等离子体原子发射光谱法(ICP-AES)测定二硼化钛增强铸铝复合材料中钛、硼、硅、镁、锌、铁。分别采用逐级稀释法、标准溶液系列使用基体匹配和无基体匹配这两种方法,考查铝的基体效应。结果表明,样品质量浓度在50~500 μg/mL范围内,铝基体对测定基本无影响。仪器选定的实验条件下,以无基体匹配的标准溶液系列绘制校准曲线,待测元素的线性方程相关系数均大于0.999 6。方法中各元素的检出限在0.000 9%~0.010%之间。将方法应用于TiB2/AlSi复合材料实际样品中钛、硼、硅、镁、锌、铁的测定,结果的相对标准偏差(RSD,n=11)均小于3%,回收率在94%~113%之间;按照实验方法测定两个铸铝标准样品中硅、镁、锌和铁,测定值与认定值一致。 相似文献
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Sergio Luis Graciano Petroni 《粉末冶金学》2020,63(1):35-42
ABSTRACTThe suitability of compaction equations commonly used in PM was investigated for the modelling of TiH2 powder compaction. Compressibility data of TiH2 powder fractions (<45, <150 and <355?μm) were obtained up to 800?MPa and fitted to the Heckel equation, as well as to the models of Gerdemann and Jablonski and Cooper and Eaton. Although a partial correlation was observed for the Heckel equation, the model provided a consistent approximation of TiH2 powder yield strength. An accurate fit was observed for the Gerdemann and Jablonski equation; however, considering the brittleness of TiH2, a more realistic depiction of the physical process was verified from the Cooper and Eaton model. By the addition of an exponential term to the original equation an excellent fit was attained, and compaction of TiH2 powders could be appropriately described according to the mechanisms of initial density, particle rearrangement, fragmentation and plastic deformation. 相似文献
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V. D. Dobrovol’skii O. G. Radchenko Yu. M. Solonin V. B. Muratov I. A. Morozov 《Powder Metallurgy and Metal Ceramics》2006,45(9-10):485-492
Methods have been applied from scanning electron microscopy, hydrogen thermal desorption, XRD, and differential thermal analysis on the effects of grain size and alloying with boron as regards the thermal stability and decomposition temperatures of hydride phases in mechanical alloys in the Ti-B-H system. The alloys were prepared by high-energy processing for 50 h in a planetary ball mill with mixtures of TiH1.9 + 9 mass% B + 13 mass% Ti and also with TiH1.9 + 50 mass% TiB2 at speeds of 1000 rpm, in addition to mixtures of TiH1.9 + 40 mass% B and TiH1.9 + 50 mass% TiB2, which were treated for 20 min at speeds of 1680 rpm. The dispersal on mechanical treatment and the addition of boron to the titanium hydride powder have substantial effects on the thermal stability. The processing of the mixture TiH1.9 + 9 mass% B + 13 mass% Ti lasting 50 h in argon gave temperatures for the dissociation of the Ti(B, H)x hydride phase in the mechanical alloy lower by 300 deg than the decomposition temperature for the initial titanium hydride TiH1.9. The mechanisms have been identified for the effects of the dispersal and boron alloying on the thermal stability of the titanium hydride. 相似文献
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A. V. Kasimtsev Yu. V. Levinskii V. V. Zhigunov 《Russian Journal of Non-Ferrous Metals》2009,50(3):270-275
The goal of this study is to investigate the mechanism and kinetics of carbidization of the titanium nickelide powder, which allows one to obtain the Ni-TiC composite powder. It is established by experimental methods and theoretical analysis that, in the temperature range 1000–1200°C, this process proceeds in the internal mode with the decomposition of NiTi and with the formation of a nickel-based solid solution with dispersed titanium carbide particles distributed in it. It is shown that, with the carbon excess in the starting charge, the final product consists of a nickel matrix, including ~3 at % carbon and traces of titanium, and particles of almost stoichiometric titanium carbide. With the deficiency of carbon in the starting charge, the Ni matrix contains ~1.1 × 10?2 at % carbon and >0.65 at % titanium, while the particles of titanium carbide have the composition TiC0.5-TiC0.8. The suggested model of this process allows one to evaluate the time that the NiTi particles completely decompose and qualitatively describe the time dependence of the particle size of titanium carbide. 相似文献