超声场对不同粗糙度的辐射杆端面空蚀行为的影响
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摘要
为了探究超声铸造用辐射杆端面不同粗糙度对空蚀孕育期的影响,对4种不同粗糙度的辐射杆用TC4钛合金进行了铝熔体空蚀实验,利用失重法分析和微观形貌检测得出了不同粗糙度表面空蚀机制的差异。对空蚀机理和固液界面反应层进行了分析。结果表明,粗糙度大的表面空蚀程度更大。其原因是:粗糙度大的表面平整性较差,增大了固液接触面积,提高了其扩散和化学反应速率;粗糙度大的表面生成的TiAl_3反应层较为疏松,易在流动的铝熔体冲刷下脱离钛合金基体;同时空化效应使表面更早形成TiAl_3,反应层裂纹等表面缺陷较多。
In order to investigate the influence of different roughness of the end surface of the radiant rod for ultrasonic casting on the cavitation incubation period, the aluminum melt cavitation test of TC4 titanium alloy for radiant rod with 4kinds of different roughnesses was carried out, and the difference of cavitation erosion mechanism on different roughness surfaces was obtained by weight loss analysis and microscopic morphology detection. The mechanism of cavitation and the reaction layer at the solid-liquid interface were analyzed. The results show that the cavitation of surface with large roughness is greater. The reasons are that the surface smoothness with large roughness is poor, the solid-liquid contact area is increased,and the diffusion and chemical reaction rates are increased; the TiAl_3 reaction layer formed on the surface with high roughness is relatively loose, and it is easy to break away from the titanium alloy matrix under the flowing aluminum melt scouring;at the same time, the cavitation effect makes the surface form TiAl_3 earlier, and there are more cracks defects in the reaction layer.
In order to investigate the influence of different roughness of the end surface of the radiant rod for ultrasonic casting on the cavitation incubation period, the aluminum melt cavitation test of TC4 titanium alloy for radiant rod with 4kinds of different roughnesses was carried out, and the difference of cavitation erosion mechanism on different roughness surfaces was obtained by weight loss analysis and microscopic morphology detection. The mechanism of cavitation and the reaction layer at the solid-liquid interface were analyzed. The results show that the cavitation of surface with large roughness is greater. The reasons are that the surface smoothness with large roughness is poor, the solid-liquid contact area is increased,and the diffusion and chemical reaction rates are increased; the TiAl_3 reaction layer formed on the surface with high roughness is relatively loose, and it is easy to break away from the titanium alloy matrix under the flowing aluminum melt scouring;at the same time, the cavitation effect makes the surface form TiAl_3 earlier, and there are more cracks defects in the reaction layer.
引文
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[2]黎正华.超声外场辅助铸造抑制7050合金宏微观偏析的实验研究[D].长沙:中南大学,2011.
[3]石婷,张忠涛,张宇博,等.功率超声对A356合金除气效果的影响[J].铸造,2010,59(6):546-548.
[4]陆岩.用超声波测试结晶器电磁搅拌对钢坯夹杂物分布的影响[J].钢铁研究学报,1992(1):31-33.
[5] Dong F, Li X Q, Zhang L H, et al. Cavitation erosion mechanism of titanium alloy radiation rods in aluminum melt[J]. Ultrasonics Sonochemistry, 2016,31:150-156.
[6]卢义刚,宋恒玲.超声波对盐酸腐蚀锌的影响[J].华南理工大学学报:自然科学版,2011,39(8):77-81.
[7]罗贤能,赵良举,奉策强,等.声空化气泡成长及破裂研究[J].工程热物理学报,2011,32(1):17-20.
[8] Wu Y J,Lan T. Study on infiltration combustion synthesis(ICS)of TiAl intermetallic compound[J]. Rare Metal Materials and Engineering,1996,25(2):17-20.
[9]董方.铝合金超声铸造中钛合金辐射杆空蚀机理及表面防护[D].长沙:中南大学,2016.
[10] Kattner U R,Lin J C,Chang Y A. Thermodynamic assessment and calculation of the Ti-Al system[J]. Metallurgical and Materials Transactions A, 1992, 23(8):2081-2090.
[11]彭搏涛,李晓谦,张立华,等.钛合金超声辐射杆在高温铝熔体中的腐蚀行为研究[J].热加工工艺,2017,46(6):119-122.
[12]关昕.钛及Ti-6Al-4V合金的空蚀行为研究[D].天津:天津大学,2010.