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.