Electroless Ni—P—ferrite composite coatings for microwave applications

Electroless, EL coating technique is one of the elegant ways of coating by controlling the temperature and pH of the coating bath in which there is no usage of electric current. It is estimated that the market for this chemistry will increase at a rate of about 15% per year. Use of microwave energy for synthesis of material with novel microstructures is an exciting new field in material science with enormous application. In this investigation, nanograined BaZn_2−yCo_yFe₁₆O₂₇ y = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0) powders have been synthesized by citrate precursor method followed by heat treatment at various specified temperatures like 650, 750 and 850° C for 3 h in the furnace. In addition heat treatments are also carried out in the microwave oven of the power rating of 760 W. The powders thus produced have been characterized by SEM, EPMA, VSM, XRD and thermal analysis techniques. As a forward step towards EL nano-composite coatings, Ni-P-X (X = BaZn_2−y Co_yFe₁₆O₂₇) coatings with thickness less than ∼0.1 mm thick has been produced. Such coating exhibits absorption of microwave in the range of 12–18 GHz up to about 20 db depending upon the volume fraction of the ferrite particles embedded in the Ni-P matrix