Preparation Technology And Mechanism Effect Of Plasma Discharge Ball Milling Of Flake Metal Functional Powder

The sheet metal functional powder has unique structure and performance,which makes it widely used in military and civil fields.For example,flake Al powder with a diameter of 30?±5??m and flake carbonyl Fe powder with a diameter of 10?±5??m have excellent infrared stealth performance and radar stealth performance,respectively,and flake zinc powder with an average particle size of 20?m With its good coverage and corrosion resistance,it occupies most of the market share of anticorrosive decorative coatings on the surface of steel structures such as vehicles and ships.However,the current industrial method for preparing sheet metal powder with excellent performance often has defects such as high cost,complicated process,and serious pollution.Therefore,there is an urgent need to explore a method for preparing sheet metal powder with lower cost,simple process and higher efficiency.In the preliminary exploration of the research group,it has been found that plasma ball milling can efficiently prepare sheet metal W powder and Ti powder.Inspired by this,this article will explore the plasma ball milling process and mechanism of three metals with different crystal structures and different melting points?aluminum,iron carbonyl,and zinc?.First of all,in the study of flake Al powder,three ball milling methods of ordinary ball milling,Ar plasma ball milling and NH₃ plasma ball milling were set up respectively.Efficient preparation method.The results show that the morphology of Al powder prepared by NH₃ plasma ball milling with"low discharge intensity+low mechanical strength"is good,with a diameter of about 30?±5??m.The infrared emissivity of the coating obtained by spraying the flake aluminum powder prepared by this process is 0.6,and the glossiness is as low as 35;under the same spraying process,the infrared emissivity of the coating of military aluminum powder is 0.5,but the glossiness is Up to 95.It can be seen that the flake aluminum powder prepared by plasma ball milling has greater advantages in infrared-visible light compatible stealth performance.In addition,by comparing the microstructure and composition of the Al powders obtained by the three ball milling methods,combined with simulation calculations,the mechanism of preparing flaky Al powder by NH₃ plasma ball milling is summarized as:the weak"electric-thermal"coupling field effect of NH₃ plasma,The Al powder retains a certain brittleness,and at the same time,a small amount of gas-solid reaction forms Al N in situ,causing a large electric field distortion,resulting in an ultra-high temperature?7.8×10³??in the distortion area,forming a molten hole on the surface of the Al substrate,thereby further promoting the powder The flaking and thinning.Secondly,in the exploration of flaky carbonyl Fe powder,three methods of ordinary ball milling,normal pressure Ar plasma ball milling and negative pressure Ar plasma ball milling were designed,respectively,for the diameter of 10?±5??m and the thickness of<1?m The preparation process of flaky carbonyl Fe powder was investigated.The results show that:"High discharge strength+low mechanical strength"negative pressure Ar plasma ball milling can effectively prepare carbonyl Fe powder with good morphology,its particle size is concentrated in 5?10?m,and the diameter to thickness ratio?50?100?:1.The mechanism can also be summarized as:low-pressure discharge improves the discharge intensity and aggravates the electroplastic effect.At the same time,the temperature in the tank exceeds the recrystallization temperature of iron carbonyl,which further strengthens the plasticity of the powder and appears under the action of the stress of the grinding ball.Shape and refine.Finally,in the exploration of flake Zn powder,three methods of ordinary ball milling,negative pressure Ar plasma ball milling and low filling ratio negative pressure Ar plasma ball milling were designed,respectively.The flake Zn powder with a diameter of 20?±5??m The ball mill preparation process was explored.The results show that the flake-shaped Zn powder prepared by negative pressure Ar plasma ball milling with"high discharge strength+high mechanical strength"and low filling ratio has a diameter of about 20?±5??m,D₅₀ between15 and 28?m,and loose The packing density is 1.3 g/m L,and the shape parameters are in accordance with the requirements of FZP-1 in the national standard GB/T26035-2010.The formation mechanism can be summarized as follows:the"electricity-heat"coupling effect provided by the high discharge intensity makes the temperature in the tank higher than the industrial hot rolled Zn ingot?150??,which greatly improves the plasticity of the Zn powder and is lower The filling ratio increases the input of mechanical energy and further promotes the flake and refinement of the powder.