包套轧制—粉末冶金法制备泡沫铝夹心板材料的研究
发布时间：2018-08-05 13:10
【摘要】：泡沫铝夹心板具有质轻、比强度及比刚度高等特点,克服了泡沫铝裸板强度偏低、表面处理及难于连接等问题,在汽车制造、航空、航天、轨道交通等领域具有广阔的应用前景,是多孔泡沫金属应用制品开发与理论研究的热点方向。目前,泡沫铝夹心板主要采用胶粘和热压-粉末冶金发泡工艺,制品板/芯结合强度低,耐高温能力差,生产效率低。因此,开发出一种高效率、短流程的泡沫铝夹心板制备新技术具有重要的应用价值及理论意义。 在国家自然科学基金项目(No.50704012)和沈阳市科技计划项目(F10-205-1-59)的资助下,本文开展了泡沫铝夹心板制备新技术的开发与理论研究工作。为提高粉末利用率,改善板型质量,提出了包套轧制-粉末冶金法制备泡沫铝夹心板的工艺路线。系统研究了主要工艺参数对发泡效果的影响,探讨了轧制压下率、发泡温度、发泡时间与泡沫铝夹心板芯层泡沫结构间的关系。分析了面板/芯层粉末的结合机制,确定了优化的制备工艺条件。通过对发泡剂TiH2进行的表面处理明显改善了泡沫结构的均匀性与稳定性,并对泡沫结构的演化过程及稳定化机理进行了深入分析,测试了夹心板的主要力学性能,并从泡沫结构与面板/芯层结合状态角度探讨了夹心板组织对力学性能的影响,论文取得了以下有价值的结果： 1.采用包套轧制的方法可显著提高粉末利用率,轧制后混合粉末基本无流失,粉末利用率接近100%,并且包套轧制过程中芯层粉末沿轧件宽度的变形行为趋于一致,使预制坯在保证芯层粉末获得极高致密度,同时粉末整体的均匀性也明显改善；综合考虑粉末致密度与板/芯结合效果轧制压下率应控制在60%-70%为宜。 2.利用自制钢制模具可实现预制坯的快速受限发泡,发泡时间由以往自由发泡工艺的8～10min缩短至1～2min,降低了破孔及连通孔的形成几率。受限发泡保证了泡沫铝夹心板具有良好的厚度精度。本研究中理想的发泡工艺为：发泡温度为700℃,发泡时间60s-70s。 3.对发泡剂TiH2进行表面改性处理可调整其分解释氢过程,使发泡剂的释氢峰值温度与释氢量符合发泡工艺要求,本研究中发泡剂的最佳热处理工艺为500℃保温60min。 4.在铝硅合金中添加一定含量的镁,能够提高合金的常温力学性能和改善加工性能,通过Mg颗粒的添加,增加了熔体的黏度,从而减小普拉特奥边界与泡壁之间的压差而使泡孔稳定性提高。本研究中理想的Mg添加量为1.0wt.%左右,能够使熔体粘度增强,显著提高泡沫铝泡孔的稳定性。 5.泡沫铝夹心板进行三点弯曲测试数据显示,本研究制备的泡沫铝夹心板的最大载荷为0.86kN～0.96kN,明显高于胶粘泡沫铝夹心板0.47kN～0.87kN的弯曲承载水平,夹心板破坏后面板与芯层间界面仍保持完整,未出现界面分离与面板褶皱。由载荷-位移曲线可知本研究制备的泡沫铝夹心板具有良好的能量吸收能力。 6.本研究制备的泡沫铝夹心板具有较好的冲击性能,最大冲击载荷为0.73kN～1.24kN,增加面板厚度与泡沫铝芯层厚度均有助于提高夹心板的冲击强度。
[Abstract]:The foam aluminum sandwich plate has the characteristics of light weight, high specific strength and high specific stiffness. It overcomes the problems of low strength, surface treatment and difficult connection, and has a broad application prospect in the fields of automobile manufacturing, aviation, aerospace and rail transportation. It is a hot direction in the development and theoretical Research of porous foam metal application products. The foam aluminum sandwich plate mainly adopts adhesive and hot press powder metallurgy foaming process. The bonding strength of the product plate / core is low, the ability of resisting high temperature is poor, and the production efficiency is low. Therefore, it has important application value and theoretical significance to develop a new technology for the preparation of high efficiency and short flow foam aluminum sandwich plate.
Under the support of the National Natural Science Foundation Project (No.50704012) and the Shenyang Municipal Science and technology project (F10-205-1-59), this paper has carried out the development and theoretical research of the new technology for the preparation of the foam aluminum sandwich plate. In order to improve the powder utilization rate and improve the quality of the plate type, a process route for the preparation of the foam aluminum sandwich plate by the package rolling and powder metallurgy is put forward. The effect of the main technological parameters on the foaming effect was systematically studied. The relationship between the rolling press rate, the foaming temperature, the foaming time and the foam structure of the sandwich plate core of the aluminum foam was discussed. The combination mechanism of the panel / core powder was analyzed, and the optimized preparation conditions were determined. The surface treatment of the foaming agent TiH2 was obviously modified. The uniformity and stability of the foam structure are good, the evolution process and the stabilization mechanism of the foam structure are deeply analyzed. The main mechanical properties of the sandwich plate are tested. The influence of the sandwich plate on the mechanical properties of the sandwich plate is discussed from the angle of the combination of the foam structure and the panel / core. The following results are obtained.
1. the use of package rolling can greatly improve the powder utilization rate. After rolling, the mixture powder basically has no loss and the powder utilization ratio is close to 100%. And the deformation behavior of the core powder along the width of the rolled piece tends to be consistent during the rolling process, making the preform high density in the core powder and the uniformity of the powder as a whole is also obvious. Improvement. Considering the effect of powder density and plate / core bonding effect, the rolling reduction rate should be controlled at 60%-70%.
2. with the self-made steel mould, the fast limited foaming of the preform can be realized. The foaming time is reduced to 1 ~ 2min from the previous free foaming process to 1 ~ 2min, which reduces the formation probability of the broken hole and the connecting hole. The limited foaming ensures the good thickness accuracy of the foam aluminum sandwich plate. The ideal foaming process in this research is the foaming temperature for the research. 700 C, foaming time 60s-70s.
3. the surface modification of the foaming agent TiH2 can adjust its decomposing hydrogen release process, which makes the peak hydrogen release temperature and the hydrogen release quantity conform to the foaming process requirements. The optimum heat treatment process of the foaming agent in this study is 60min. heat preservation.
4. adding a certain amount of magnesium to Al Si alloy can improve the mechanical properties of the alloy at normal temperature and improve the processing property. By adding Mg particles, the viscosity of the melt is increased, thus reducing the pressure difference between the Platt orifice boundary and the bubble wall to improve the stability of the bubble hole. In this study, the ideal Mg amount is about 1.0wt.%, which can make the melt melt. The viscosity of the foam increases, and the stability of the foams is improved significantly.
The three point bending test data of the 5. foam aluminum sandwich panel shows that the maximum load of the aluminum sandwich plate prepared by this study is 0.86kN ~ 0.96kN, which is obviously higher than the bending bearing level of the adhesive aluminum sandwich panel 0.47kN to 0.87kN. The interface between the panel and the core layer remains intact after the sandwich plate failure, and there is no interface separation and panel folds. The load displacement curve shows that the foam aluminum sandwich panel prepared by this study has good energy absorption capability.
6. the foam aluminum sandwich plate prepared by this study has good impact performance and the maximum impact load is 0.73kN to 1.24kN. The increase of the thickness of the panel and the thickness of the foam aluminum core will help to improve the impact strength of the sandwich plate.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TB383.4
本文编号：2165895
[Abstract]:The foam aluminum sandwich plate has the characteristics of light weight, high specific strength and high specific stiffness. It overcomes the problems of low strength, surface treatment and difficult connection, and has a broad application prospect in the fields of automobile manufacturing, aviation, aerospace and rail transportation. It is a hot direction in the development and theoretical Research of porous foam metal application products. The foam aluminum sandwich plate mainly adopts adhesive and hot press powder metallurgy foaming process. The bonding strength of the product plate / core is low, the ability of resisting high temperature is poor, and the production efficiency is low. Therefore, it has important application value and theoretical significance to develop a new technology for the preparation of high efficiency and short flow foam aluminum sandwich plate.
Under the support of the National Natural Science Foundation Project (No.50704012) and the Shenyang Municipal Science and technology project (F10-205-1-59), this paper has carried out the development and theoretical research of the new technology for the preparation of the foam aluminum sandwich plate. In order to improve the powder utilization rate and improve the quality of the plate type, a process route for the preparation of the foam aluminum sandwich plate by the package rolling and powder metallurgy is put forward. The effect of the main technological parameters on the foaming effect was systematically studied. The relationship between the rolling press rate, the foaming temperature, the foaming time and the foam structure of the sandwich plate core of the aluminum foam was discussed. The combination mechanism of the panel / core powder was analyzed, and the optimized preparation conditions were determined. The surface treatment of the foaming agent TiH2 was obviously modified. The uniformity and stability of the foam structure are good, the evolution process and the stabilization mechanism of the foam structure are deeply analyzed. The main mechanical properties of the sandwich plate are tested. The influence of the sandwich plate on the mechanical properties of the sandwich plate is discussed from the angle of the combination of the foam structure and the panel / core. The following results are obtained.
1. the use of package rolling can greatly improve the powder utilization rate. After rolling, the mixture powder basically has no loss and the powder utilization ratio is close to 100%. And the deformation behavior of the core powder along the width of the rolled piece tends to be consistent during the rolling process, making the preform high density in the core powder and the uniformity of the powder as a whole is also obvious. Improvement. Considering the effect of powder density and plate / core bonding effect, the rolling reduction rate should be controlled at 60%-70%.
2. with the self-made steel mould, the fast limited foaming of the preform can be realized. The foaming time is reduced to 1 ~ 2min from the previous free foaming process to 1 ~ 2min, which reduces the formation probability of the broken hole and the connecting hole. The limited foaming ensures the good thickness accuracy of the foam aluminum sandwich plate. The ideal foaming process in this research is the foaming temperature for the research. 700 C, foaming time 60s-70s.
3. the surface modification of the foaming agent TiH2 can adjust its decomposing hydrogen release process, which makes the peak hydrogen release temperature and the hydrogen release quantity conform to the foaming process requirements. The optimum heat treatment process of the foaming agent in this study is 60min. heat preservation.
4. adding a certain amount of magnesium to Al Si alloy can improve the mechanical properties of the alloy at normal temperature and improve the processing property. By adding Mg particles, the viscosity of the melt is increased, thus reducing the pressure difference between the Platt orifice boundary and the bubble wall to improve the stability of the bubble hole. In this study, the ideal Mg amount is about 1.0wt.%, which can make the melt melt. The viscosity of the foam increases, and the stability of the foams is improved significantly.
The three point bending test data of the 5. foam aluminum sandwich panel shows that the maximum load of the aluminum sandwich plate prepared by this study is 0.86kN ~ 0.96kN, which is obviously higher than the bending bearing level of the adhesive aluminum sandwich panel 0.47kN to 0.87kN. The interface between the panel and the core layer remains intact after the sandwich plate failure, and there is no interface separation and panel folds. The load displacement curve shows that the foam aluminum sandwich panel prepared by this study has good energy absorption capability.
6. the foam aluminum sandwich plate prepared by this study has good impact performance and the maximum impact load is 0.73kN to 1.24kN. The increase of the thickness of the panel and the thickness of the foam aluminum core will help to improve the impact strength of the sandwich plate.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TB383.4
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