等離子弧制備金屬粉末裝置研制及粉末性能研究
發(fā)布時間：2018-11-03 14:06
【摘要】：以“3D打印”為代名詞的增材制造技術(shù)方興未艾,但隨著應(yīng)用領(lǐng)域日益廣泛,也技術(shù)面臨著材料種類單一,兼容性低的問題。所用粉末材料制備技術(shù)的匱乏成為了“3D”打印無法大規(guī)模工業(yè)應(yīng)用的瓶頸,使得這一新技術(shù)仍有很多問題有待解決。相較于傳統(tǒng)工業(yè)用粉末材料,增材制造要求所用粉末粒度在100μm以下、呈實心圓球狀、粒度要達到一定的比例的分布,且每一個球形小顆粒的元素分布要與原材料相近而不能有明顯偏析。這些苛刻要求成了擺在多種傳統(tǒng)制粉方法面前的挑戰(zhàn)。本文綜合分析“增材制造”對粉末材料所提技術(shù)要求,基于熔化極氣體保護焊與等離子切割原理,同時借鑒氣體動力學(xué)等技術(shù)。創(chuàng)新性地提出了利用等離子弧同向霧化金屬絲(棒)狀材料,配合反用“拉瓦爾管”原理的“擴容室”噴嘴,制備了不銹鋼、鎳基合金、鈦合金等多種球狀微米級金屬粉末。同時對粉末進行顯微形貌、粒度分布、成分與物相分析,機理研究所得結(jié)果如下:(1)單個和多個電極等離子弧同向霧化制粉,充分發(fā)揮了等離子弧高溫、高能量密度、高氣動性等優(yōu)點,更直接地實現(xiàn)了對材料的快速熔化與其后液滴的破碎細化;(2)根據(jù)超音速與亞音速等離子射流的特點,反用火箭發(fā)動機噴管原理,根據(jù)能量方程、解微分方程的龍格-庫塔法,利用流體經(jīng)過變截面區(qū)域速度、溫度與壓力變化規(guī)律計算出較合理的擴容室噴嘴外形,充分發(fā)揮了延長材料冷卻時間,同時加速吹出等離子弧高溫區(qū)的作用。將原本金屬熔滴的凝固過程分解成兩個可變速度的步驟;(3)對于外徑4-10mm的絲狀材料,在裝置輸出電流90A-110A、輸出氣體壓力0.40MPa-0.55MPa、氣體流量35L/min-55L/min;在距離等離子射流出口70mm-75mm處放置擴容室噴嘴,擴容室最小截面處半徑20.00mm、最大處半徑29.02mm、截面半角15°時�？墒沟弥苽涞姆勰┎牧贤庑胃咏蛐�,且顆粒呈現(xiàn)快速凝固的組織形貌。粉末平均粒徑57.96μm、粒度分布于30μm-100μm之間,較好實現(xiàn)了大小搭配;粉末松裝密度2.50g/cm3,振實密度2.72 g/cm3。
[Abstract]:The technology of "3D printing" is in the ascendant, but with the increasing application field, the technology is faced with the problem of single material type and low compatibility. The shortage of the preparation technology of powder materials has become the bottleneck of "3D" printing which can not be applied on a large scale, so there are still many problems to be solved in this new technology. Compared with the traditional industrial powder materials, the powder size required for the material increasing production is less than 100 渭 m, which is like a solid ball, and the particle size should be distributed in a certain proportion. The element distribution of each small spherical particle should be similar to that of raw material without obvious segregation. These harsh requirements have become a challenge in front of a variety of traditional pulverizing methods. Based on the principle of gas shielded welding and plasma cutting, the technical requirements for powder materials in "material increasing manufacture" are analyzed synthetically in this paper. At the same time, the techniques such as gas dynamics are used for reference. By using plasma arc codirectional atomizing wire (rod)-like material and the "expansion chamber" nozzle of "Laval tube" principle, a variety of spherical micron metal powders, such as stainless steel, nickel base alloy, titanium alloy and so on, have been prepared. At the same time, the microstructure, particle size distribution, composition and phase of the powder are analyzed. The results are as follows: (1) single and multiple electrode plasma arcs are atomized in the same direction to make powder, giving full play to the high temperature and high energy density of plasma arc. The advantages of high aerodynamic performance, such as the rapid melting of materials and the subsequent breakup and refinement of droplets, are realized more directly. (2) according to the characteristics of supersonic and subsonic plasma jet, the inverse rocket engine nozzle principle, according to the energy equation, the Runge-Kutta method for solving differential equations, the velocity of fluid passing through the region of variable cross section is used. The change of temperature and pressure gives a reasonable shape of the nozzle in the expansion chamber, which can extend the cooling time of the material and accelerate the blowing out of the high temperature region of the plasma arc at the same time. The solidification process of the original metal droplet is decomposed into two variable speed steps; (3) for filamentary material with outer diameter 4-10mm, the output current is 90A-110A, the output gas pressure is 0.40MPa-0.55MPa, the gas flow rate is 35L / min-55L / min; The nozzle of the expansion chamber is placed at the 70mm-75mm exit of the plasma jet. The minimum section radius of the expansion chamber is 20.00 mm, the maximum radius is 29.02 mm, and the cross-section angle is 15 擄. The morphology of the prepared powder materials is more spherical and the particles exhibit the microstructure of rapid solidification. The average particle size of the powder is 57.96 渭 m and the particle size distribution is between 30 渭 m and 100 渭 m. The powder bulk density is 2.50 g / cm 3 and the vibrational density is 2.72 g / cm 3.
【學(xué)位授予單位】：長春工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.3;TP391.73
[Abstract]:The technology of "3D printing" is in the ascendant, but with the increasing application field, the technology is faced with the problem of single material type and low compatibility. The shortage of the preparation technology of powder materials has become the bottleneck of "3D" printing which can not be applied on a large scale, so there are still many problems to be solved in this new technology. Compared with the traditional industrial powder materials, the powder size required for the material increasing production is less than 100 渭 m, which is like a solid ball, and the particle size should be distributed in a certain proportion. The element distribution of each small spherical particle should be similar to that of raw material without obvious segregation. These harsh requirements have become a challenge in front of a variety of traditional pulverizing methods. Based on the principle of gas shielded welding and plasma cutting, the technical requirements for powder materials in "material increasing manufacture" are analyzed synthetically in this paper. At the same time, the techniques such as gas dynamics are used for reference. By using plasma arc codirectional atomizing wire (rod)-like material and the "expansion chamber" nozzle of "Laval tube" principle, a variety of spherical micron metal powders, such as stainless steel, nickel base alloy, titanium alloy and so on, have been prepared. At the same time, the microstructure, particle size distribution, composition and phase of the powder are analyzed. The results are as follows: (1) single and multiple electrode plasma arcs are atomized in the same direction to make powder, giving full play to the high temperature and high energy density of plasma arc. The advantages of high aerodynamic performance, such as the rapid melting of materials and the subsequent breakup and refinement of droplets, are realized more directly. (2) according to the characteristics of supersonic and subsonic plasma jet, the inverse rocket engine nozzle principle, according to the energy equation, the Runge-Kutta method for solving differential equations, the velocity of fluid passing through the region of variable cross section is used. The change of temperature and pressure gives a reasonable shape of the nozzle in the expansion chamber, which can extend the cooling time of the material and accelerate the blowing out of the high temperature region of the plasma arc at the same time. The solidification process of the original metal droplet is decomposed into two variable speed steps; (3) for filamentary material with outer diameter 4-10mm, the output current is 90A-110A, the output gas pressure is 0.40MPa-0.55MPa, the gas flow rate is 35L / min-55L / min; The nozzle of the expansion chamber is placed at the 70mm-75mm exit of the plasma jet. The minimum section radius of the expansion chamber is 20.00 mm, the maximum radius is 29.02 mm, and the cross-section angle is 15 擄. The morphology of the prepared powder materials is more spherical and the particles exhibit the microstructure of rapid solidification. The average particle size of the powder is 57.96 渭 m and the particle size distribution is between 30 渭 m and 100 渭 m. The powder bulk density is 2.50 g / cm 3 and the vibrational density is 2.72 g / cm 3.
【學(xué)位授予單位】：長春工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.3;TP391.73
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