High Energy Ball Milling Sheet Permalloy Powder And Its Shielding Paint Applied Research

Permalloy,which is called Fe-Ni alloy and soft magnetic material,is commonly used in the power technology.When permalloy is used in the power technology of more than 1 MHz frequency,it will cause large eddy current loss and skin effect because permalloy has high magnetic conductivity and saturated magnetic strength,low electric resistivity.The results limit its application in higher frequency power technology.But in low frequency magnetic field,the electromagnetic shielding coating made of permalloy powder generates a low magnetic reluctance path of magnetic lines and encapsulates the majority of the magnetic field in the shielding body to separate the protected equipment because of permaUoy's high magnetic conductivity.It is researched in this article that-200 mesh spherical evaporated permalloy powder made of Fe:wt%=17%,Ni:wt%=81%,Mo:wt%=2%is preparated to the flake permalloy powder of the flake diameter d₅₀≤50μm,the flake thicknessσ≤5μm,which has good apparent morphology and dispersion property by high-energy horizontal rotary stirred ball mill.As a new type metal filler of electromagnetic shielding coating,we use the flake permalloy powder to manufacture the electromagnetic shielding coating mainly used in low frequency magnetic field whose surface electric resistivity,electromagnetic shielding effect and other physical properties meet the requirement.At first,theoretically,the properties and application of permalloy is introduced,the structure and electromagnetic properties of the experimental raw are analysed,mental powder and its application and manufacture technology are summarized,with the composition and shielding mechanism of electromagnetic shielding coating in this article. When we study the milling mechanism of high-energy horizontal rotary stirred ball mill,we introduce Benjamin Model and Maurice-Courtney Model to analyse quantitatively the factors of the collision,sports,energy transmission and temperature rise during the ball milling.Consequently we choose the M01-21 ball mill as the experimental platform.According to the high energy ball mill experiments,the factors which can impact the properties of the flake permalloy powder product,such as ball mill media,ball mill time, filling coefficient,the ratio of milling ball to powder,rotary velocity etal.,are studied experimentally.It is found that under that conditions:1.φ=4.73mm stainless steel ball,2.in inert argon atmosphere,3.0.3-0.4 filling coefficient and 2000-3000g filling load,4.60-150 min milling time,5.the ratio of milling ball to powder:about 20:1-30:1,6.rotary velocity: about 500 rpm,alternating rotary is optium,7.the stearic acid as the main dispersed agent and 2%the weight of permalloy powder raw,the spherical evaporated permalloy powder is milled to the flake permalloy powder of the flake diameter d₅₀=50μm,the flake thickness S=5μm.According to the coating experiments,the difference of the surface electric resistivities of spherical and flake permalloy powder is compared,the quantity the bulk density and the middle diameter of metal filler which can effect coating surface electric resistivity are analysed,the physical properties of the electromagnetic shielding coating are checked and the electromagnetic shielding effect is calculated.It is concluded that 1.the surface electric resistivity of the coating made of the flake permalloy powder is 0.845Ω/cm less than the spherical permalloy powder and the coating made of the flake permalloy powder has more smooth surface formation and better metallic luster,2.metal filler load,m_{å¡«æ–™}/m_{æ ‘è„‚}=4:1 is better,3.the flake permalloy powder of bulk densityρ_b=1.1-1.4g/cm³ Can make the coating surface electric resistivity less than 0.5Ω/cm,4.the flake permalloy powder of middle diameter d₅₀=17-30μm can make the electric conductivity higher and has good desperation, 5.the electromagnetic shielding effect of the coating is 45-55dB.The electromagnetic shielding coating made of flake permalloy and acrylic resin has more smooth surface formation and better metallic luster,with adhesive strength 1 grade,pencil hardness 1H and crash strength resistance≥50kg/cm.The electromagnetic shielding coating made of flake permalloy and acrylic resin can be applied in low frequency electromagnetic shielding field to protect general industrial or commercial electronic equipments...