Preparation, characterization and microwave absorption properties of electroless Ni–Co–P-coated SiC powder

Silicon carbide particles reinforced nickel–cobalt–phosphorus matrix composite coatings were prepared by two-step electroless plating process (pre-treatment of sensitizing and subsequent plating) for the application to lightweight microwave absorbers, which were characterized by scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), vibrating sample magnetometer (VSM) and vector network analyzer, respectively. The results show that Ni–Co–P deposits are uniform and mixture crystalline of α-Co and Ni3P and exhibit low-specific saturation magnetization and low coercivity. Due to the conductive and ferromagnetic behavior of the Ni–Co thin films, high dielectric constant and magnetic loss can be obtained in the microwave frequencies. The maximum microwave loss of the composite powder less than −32 dB was found at the frequency of 6.30 GHz with a thickness of 2.5 mm when the initial atomic ratio of Ni–Co in the plating bath is 1.5.