包套軋制—粉末冶金法制備泡沫鋁夾心板材料的研究
發(fā)布時間：2018-08-05 13:10
【摘要】：泡沫鋁夾心板具有質(zhì)輕、比強度及比剛度高等特點,克服了泡沫鋁裸板強度偏低、表面處理及難于連接等問題,在汽車制造、航空、航天、軌道交通等領(lǐng)域具有廣闊的應用前景,是多孔泡沫金屬應用制品開發(fā)與理論研究的熱點方向。目前,泡沫鋁夾心板主要采用膠粘和熱壓-粉末冶金發(fā)泡工藝,制品板/芯結(jié)合強度低,耐高溫能力差,生產(chǎn)效率低。因此,開發(fā)出一種高效率、短流程的泡沫鋁夾心板制備新技術(shù)具有重要的應用價值及理論意義。 在國家自然科學基金項目(No.50704012)和沈陽市科技計劃項目(F10-205-1-59)的資助下,本文開展了泡沫鋁夾心板制備新技術(shù)的開發(fā)與理論研究工作。為提高粉末利用率,改善板型質(zhì)量,提出了包套軋制-粉末冶金法制備泡沫鋁夾心板的工藝路線。系統(tǒng)研究了主要工藝參數(shù)對發(fā)泡效果的影響,探討了軋制壓下率、發(fā)泡溫度、發(fā)泡時間與泡沫鋁夾心板芯層泡沫結(jié)構(gòu)間的關(guān)系。分析了面板/芯層粉末的結(jié)合機制,確定了優(yōu)化的制備工藝條件。通過對發(fā)泡劑TiH2進行的表面處理明顯改善了泡沫結(jié)構(gòu)的均勻性與穩(wěn)定性,并對泡沫結(jié)構(gòu)的演化過程及穩(wěn)定化機理進行了深入分析,測試了夾心板的主要力學性能,并從泡沫結(jié)構(gòu)與面板/芯層結(jié)合狀態(tài)角度探討了夾心板組織對力學性能的影響,論文取得了以下有價值的結(jié)果： 1.采用包套軋制的方法可顯著提高粉末利用率,軋制后混合粉末基本無流失,粉末利用率接近100%,并且包套軋制過程中芯層粉末沿軋件寬度的變形行為趨于一致,使預制坯在保證芯層粉末獲得極高致密度,同時粉末整體的均勻性也明顯改善；綜合考慮粉末致密度與板/芯結(jié)合效果軋制壓下率應控制在60%-70%為宜。 2.利用自制鋼制模具可實現(xiàn)預制坯的快速受限發(fā)泡,發(fā)泡時間由以往自由發(fā)泡工藝的8～10min縮短至1～2min,降低了破孔及連通孔的形成幾率。受限發(fā)泡保證了泡沫鋁夾心板具有良好的厚度精度。本研究中理想的發(fā)泡工藝為：發(fā)泡溫度為700℃,發(fā)泡時間60s-70s。 3.對發(fā)泡劑TiH2進行表面改性處理可調(diào)整其分解釋氫過程,使發(fā)泡劑的釋氫峰值溫度與釋氫量符合發(fā)泡工藝要求,本研究中發(fā)泡劑的最佳熱處理工藝為500℃保溫60min。 4.在鋁硅合金中添加一定含量的鎂,能夠提高合金的常溫力學性能和改善加工性能,通過Mg顆粒的添加,增加了熔體的黏度,從而減小普拉特奧邊界與泡壁之間的壓差而使泡孔穩(wěn)定性提高。本研究中理想的Mg添加量為1.0wt.%左右,能夠使熔體粘度增強,顯著提高泡沫鋁泡孔的穩(wěn)定性。 5.泡沫鋁夾心板進行三點彎曲測試數(shù)據(jù)顯示,本研究制備的泡沫鋁夾心板的最大載荷為0.86kN～0.96kN,明顯高于膠粘泡沫鋁夾心板0.47kN～0.87kN的彎曲承載水平,夾心板破壞后面板與芯層間界面仍保持完整,未出現(xiàn)界面分離與面板褶皺。由載荷-位移曲線可知本研究制備的泡沫鋁夾心板具有良好的能量吸收能力。 6.本研究制備的泡沫鋁夾心板具有較好的沖擊性能,最大沖擊載荷為0.73kN～1.24kN,增加面板厚度與泡沫鋁芯層厚度均有助于提高夾心板的沖擊強度。
[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.
【學位授予單位】：東北大學
【學位級別】：碩士
【學位授予年份】：2011
【分類號】：TB383.4
本文編號：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.
【學位授予單位】：東北大學
【學位級別】：碩士
【學位授予年份】：2011
【分類號】：TB383.4
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