共查询到20条相似文献,搜索用时 15 毫秒
1.
分别在陶瓷类ZrO2、Y2O3、BN和Al2O3坩埚内于2053K(或2153K)保温30min(或10min)重熔铌基超高温合金(主要组分为Nb、Si、Ti、Hf等),以研究该合金的高温熔体与不同材料坩埚的反应情况。实验发现Y2O3、BN和Ai2O3坩埚对熔体都发生了不同程度的沾污反应;在ZrO2坩埚壁上出现了50~60μm厚且具有微小裂纹或熔蚀坑的反应层,其内含有HfO2和TiO2,但ZrO2坩埚对熔体内部基本没有污染。在石墨坩埚上进行制备YSZ涂层的实验发现,ZrO2同石墨基体发生反应生成了ZrC0因此,据有关实验结果,可以先在石墨坩埚基体上用CVD法制备一层SiC内层,再在SiC内层上用浸涂法制备ZrO2涂层,以用于铌基超高温合金熔炼。 相似文献
2.
3.
A. J. Sunwoo J. W. Morris G. K. Lucey 《Metallurgical and Materials Transactions A》1992,23(4):1323-1332
This article reports a comparative study of the formation and growth of intermetallic phases at the interface of Cu wetted
with a thick solder joint or a thin, pretinned solder layer. The η phase (Cu6Sn5) forms when Cu is wet with eutectic solder at temperatures below 400 °C. The intermetallic layer is essentially unaffected
by aging at 70 °C for as long as 13 weeks. On aging a eutectic joint at 170 °C, the η-phase intermetallic layer thickens and
ε phase (Cu3Sn) nucleates at the Cu/intermetallic interface and grows to a thickness comparable to that of the η phase, while a Pb-rich
boundary layer forms in the solder. The aging behavior of a thin, pretinned eutectic layer is qualitatively different. At
170 °C, the Sn in the eutectic is rapidly consumed to form η-phase intermetallic, which converts to ε phase. The residual
Pb withdraws into isolated islands, and the solderability of the surface deteriorates. When the pretinned layer is Pb-rich
(95Pb-5Sn), the Sn in the layer is also rapidly converted into η phase, in the form of dendrites penetrating from the intermetallic
at the Cu interface and discrete precipitates in the bulk. How ever, the development of the intermetallic largely ceases when
the Sn is consumed; ε phase does not form, and the residual Pb remains as an essentially continuous layer, preserving the
solderability of the sample. These observations are interpreted in light of the Cu-Sn and Pb-Sn phase diagrams, the temperature
of initial wetting, and the relative diffusivities of Cu and Sn in the solder and intermetallic phases.
A.J. SUNWOO, Formerly with the Lawrence Berkeley Laboratory, Berkeley, CA, 相似文献
4.
研究了Nb-35Ti-6Al、Nb-15Ti—llAl以及Nb-30Ti-15Al三组合金于900℃和1000℃在空气中的氧化行为,建立了Nb-Ti—A1合金高温氧化动力学模型。研究表明,元素Ti和Al的加入能有效改善合金的抗氧化性能,合金中占相的存在降低了氧的溶解度。同时抑制氧的扩散,因而两相合金Nb-15Ti-llAl和Nb-30Ti-15Al(β+δ相)抗氧化性能优于单相合金Nb-35Ti-6Al(β相)。 相似文献
5.
6.
A. Cervellon J. Cormier F. Mauget Z. Hervier Y. Nadot 《Metallurgical and Materials Transactions A》2018,49(9):3938-3950
Very high cycle fatigue (VHCF) properties at high temperature of Ni-based single-crystal (SX) superalloys and of a directionally solidified (DS) superalloy have been investigated at 20 kHz and a temperature of 1000 °C. Under fully reversed conditions (R = ? 1), no noticeable difference in VHCF lifetimes between all investigated alloys has been observed. Internal casting pores size is the main VHCF lifetime-controlling factor whatever the chemical composition of the alloys. Other types of microstructural defects (eutectics, carbides), if present, may act as stress concentration sites when the number of cycles exceed 109 cycles or when porosity is absent by applying a prior hot isostatic pressing treatment. For longer tests (> 30 hours), oxidation also controls the main crack initiation sites leading to a mode I crack initiation from oxidized layer. Under such conditions, alloy’s resistance to oxidation has a prominent role in controlling the VHCF. When creep damage is present at high ratios (R ≥ 0.8), creep resistance of SX/DS alloys governs VHCF lifetime. Under such high mean stress conditions, SX alloys developed to retard the initiation and creep propagation of mode I micro-cracks from pores have better VHCF lifetimes. 相似文献
7.
介绍了采用连铸连轧工艺生产φ20mm铜锡合金线坯的过程,分析了线坯氧含量、锡含量对生产稳定性的影响。阐述了拉拔机冷拉成型接触线的工艺过程,对产品的抗拉强度、延伸率等性能指标进行了研究及对比。 相似文献
8.
9.
高速电气化铁道用铜锡合金接触线的开发 总被引:1,自引:0,他引:1
介绍了采用连铸连轧工艺生产φ20mm铜锡合金线坯的过程,分析了线坯氧含量、锡含量对生产稳定性的影响.阐述了拉拔机冷拉成型接触线的工艺过程,对产品的抗拉强度、延伸率等性能指标进行了研究及对比. 相似文献
10.
11.
高温合金表面激光熔铸镍基合金涂层的组织与耐磨性能 总被引:8,自引:0,他引:8
研究了高温合金GH33表面激光熔铸镍基合金涂层的组织和耐磨性能。结果表明,基材对涂层合金的稀释作用较小;涂层与基材之间形成良好的冶金接合;涂层基体组织为γ-Ni枝晶,枝晶间为γ-Ni、M23(CB)6、Ni3B、Cr2B、CrB、WC等;涂层耐磨性能的平均值较基材提高4倍以上。 相似文献
12.
Based on the Miedema's formation heat model for binary alloys and the Toop's asymmetric model for ternary alloys, the formation heat, excess entropy, and activity coefficients of silicon ranging from 1 900 K to 4 100 K in the Fe-Si-C melt formed during the laser cladding high silicon coatings process were calculated. The results indicated that all values of lnγ^0Si, ε^CSi,ρ^SiSi and ρ^CSi are negative in the temperature range and these values increase as the temperature increases. And all values of ε^SiSi and ρ^Si-CSi are positive and these values decrease with increasing temperature. The iso-activity lines of silicon are distributed axisymmetrically to the incident laser beam in the melt pool vertical to the laser scanning direction. And the iso-activity lines of silicon in the front of the melt pool along the laser scanning direction are more intensive than those in the back of the melt pool. The activity of silicon on the bottom of the melt pool is lower than that in the effecting center of laser beam on the top surface of the melt pool and it may be the important reason for the formation of the silicides and excellent metallurgical bonding between the laser cladding coating and the substrate. 相似文献
13.
Thesurfacetransversalcrackonacontinuouscastingslabisthoughttoberelatedtothedefectsontheslabsurfacesuchasthelardandthevibrationtraceontheinnerarcsideofslab ,anditgeneratesinthesecondarycoolingzoneofcontinuouscastingpro cess .Inordertodeterminethedeformationtemper atureofslabinthesecondarycoolingzoneofthecontinuouscastingprocess ,thethermalplasticityofsteelismeasuredinthermalmechanicalsimulatorus ingcontinuoussampleontheassumptionthatthecontinuouscastingslabisauniformandcontinuousonewithoutanydef… 相似文献
14.
15.
几何结构影响高温空气燃烧特性的数值分析 总被引:1,自引:0,他引:1
通过改变燃料喷口周围空气喷口分布夹角,采用数值计算的方法研究了高温空气燃烧特性的变化,包括燃烧温度场、速度场和NOx的生成和出口排放情况。模拟结果说明,减小空气分布夹角可以降低燃烧区最高温度和平均温度,扩大燃烧室内低氧范围,有效抑制热力型NOx的生成和排放。所采用的计算模型和计算方法可以较好地模拟高温空气燃烧过程,计算结果可信。 相似文献
16.
在很宽的钢水质量范围内对包括钢包炉和多种真空处理在内的二次冶金工艺的成本进行了分析,并对两种常用的真空泵系统进行了比较。干式机械真空泵在最多360t的整个钢水质量范围内都具有明显的成本优势,节约的幅度随工艺而变化,具体同能源(无论何种形式)的供应和设备的产能有关。通过快速抽真空缩短处理的周期时间,降低了钢水的过热需要,从而降低了生产成本,提高了产能,改善了质量。 相似文献
17.
18.
介绍了不同形式热风炉的特点和结构稳定性,针对鞍钢4号高炉增建4号热风炉采用的新技术-近似悬链线拱顶、烟气分配、冷风分配、圆形火井、板块结构、滑动缝、膨胀缝、不锈钢隔板、七孔格子砖以及组合砖等进行了介绍,同时对在有预热技术的情况下,有效地提高风温问题进行了探讨。 相似文献
19.
LONG Shigang CAO Feng WANG Siwei SUN Liuheng PANG Jianming SUN Yuping 《钢铁研究学报(英文版)》2008,15(1):6-0
To study the combustion characteristics of the polyethylene(PE)particle and coal powder at blast temperature of the blast furnace,the contents of CO and CO2 of off-gas during the combustion of PE particle and coal powder at the 1 200 ℃ and 1 250 ℃ were measured using carbon monoxide and carbon dioxide infrared analyzer,and then the corresponding combustion ratio was calculated.The results showed that when the temperature is high,the combustion speed of PE and coal powder is high and the corresponding combustion ratio is high.Whereas,the combustion speed and ratio of PE are much higher than those of coal powder. 相似文献
20.
试验用NM360钢(/%:0.17C,0.38Si,1.28Mn,0.014P,0.005S,0.23Cr,0.14Mo,0.02Ti,0.04Al)30mm厚板的生产工艺流程为90t EAF-LF-VD-180mm×1330mm坯连铸-轧制30mm板-950℃淬火,350℃回火。利用Gleeble-3500热模拟试验机研究了耐磨钢NM360在900~1200℃,应变速率为0.1、1、10s-1下的变形行为,确定了NM360耐磨钢的热变形方程,建立了热加工图。结果表明,利用Zener-Hollomon参数可很好描述NM360钢热压缩变形时的流变特性,计算的动态再结晶激活能为305kJ/mol。随着温度升高以及应变速率降低,能量耗散效率逐渐升高;在1100℃,应变速率为0.1s-1时,变形能量耗散效率达到最大值0.34。该耐磨钢在1070~1170℃,应变速率0.1~0.5s-1时,具有较好的变形能力。通过优化工艺的生产结果表明,180mm铸坯(1200±20)℃加热,(1050±10)℃开轧,(950±10℃终轧成30mm板、水冷,350~550℃回火1h,NM360钢HB硬度值为368~385,屈服强度830~920MPa,抗拉强度1030~1120MPa,延伸率10%~15%,具有良好的力学性能。 相似文献