Chin-Fe-B sintered permanent magnetic material surface modification technology

Chin-Fe-B sintered permanent magnetic material surface modification technology
　　Chin-iron on the third generation of thin boron (NdFeB) permanent magnet materials have high saturation magnetic flux, coercivity and energy product Yin Diao. ux, good machining properties and relatively low prices in many areas to be widely used. However, the chemical stability of NdFeB permanent magnet material difference in the use of environment prone to oxidation, and in severe hot and humid conditions, the electrochemical corrosion will significantly affect the scope of its application. The corrosion resistance of NdFeB permanent magnetic materials is the focus of attention at home and abroad, because it is directly related to the use of magnets, the NdFeB permanent magnetic materials for surface protection technology is of great significance.
　　This paper reviews the recent sintered NdFeB permanent magnetic materials processing research corrosion mechanism and protection, based on the sol-gel coating, phosphate coating, nano-composite plating plus i n a 02 layer, and composite coatings for sintered NdFeB permanent magnet material of surface protection.
　　Inorganic magnesium salt as precursor, ethanol as solvent, adding an appropriate amount of surfactant, sol-gel method using sintered NdFeB permanent magnets in the first successful preparation of the MgO surface film. A discussion of the different l: Arts and conditions on the stability of sol-gel, using xRD, DSC GA and static corrosion tests of a characterization of the film structure and properties, the results show that: (1) the concentration of magnesium ions in the precursor 0.03 ~. .15 Mol of a, range, ethanol and surfactants (collodion) when the volume ratio = 6:4-8:2, can be prepared in a transparent and stable sol: (2) the best in the heat treatment process sintered NdFeB permanent magnetic materials formed on the surface of the compact, corrosion of the MgO film, and grain orientation on MgO (200) and (220) materials surface, after heat treatment at 450 ℃ average grain size of MgO 23.43lun .
　　Of sintered NdFeB permanent magnet material in the surface of non-toxic, non-polluting phosphate coating the surface of the ways to solve the corrosion problem. Discussed the pre-treatment process, composed of phosphate solution, phosphate film forming temperature, phosphate film time on the preparation of phosphate coating. Using optical microscopy (OM), SEM, potentiodynamic polarization curves and static corrosion tests to characterize the phosphate coating film forming and corrosion resistance, the optimum film forming process parameters. The results show: phosphating using newly developed formula and process sintered NdFeB permanent magnet material in the surface can form dense phosphate coating, the phosphate film can be effectively sintered NdFeB http://www.everbeenmagnet.com/ permanent magnet material corrosion protection.
　　Ni plating solution as an ordinary base fluid, adding different crystal nano TIO: particles, sintered NdFeB permanent magnets in the implementation of nano-composite coating surface. By XRD, the structure of nano-composite coatings, using potentiodynamic polarization curves, static corrosion tests, porosity tests and to characterize the binding force detection performance of nano-composite coatings. XRD analysis showed that nano-particles doping TIOZ, did not change the structure of matrix metal Ni plating, and composite coatings TIO: and Ni respectively, at a specific point of the diffraction peaks; through the detection of corrosion resistance, adhesion strength test and porosity tests show that the composite coatings with excellent corrosion protection performance, and the coating and the sintered NdFeB permanent magnetic materials to the combination of strong, low porosity.
　　To get a better corrosion protection layer, sintered NdFeB permanent magnets in the implementation of the composite coating surface, the first application of phosphating process in the preparation of phosphate coating the surface of sintered NdFeB, its sintered permanent magnetic material  for the intermediate layers and then apply the power deposition Preparation of the phosphate composite coating film surface. Tested by XRD, XPS test, potentiodynamic polarization curves, static corrosion tests, porosity tests and adhesion tests to characterize the performance of composite film. The results show that the composite film can greatly improve the surface of sintered NdFeB permanent magnet resistance Can performance.