Study on Ni/P-coating deposition and interface behavior in solid-solid/solid-liquid compositing process

Electroless Ni/P coating was obtained on the carbon-material substrate of graphite blocks and woven carbon fibers through a new plating solution, and three different temperatures and pH values were respectively adopted during the deposition process. The lactic acid presented an excellent stability capability, and the coatings with compact structure and appropriate P content could be generated under 343 K and pH 4.0, the reaction activation energy of which was around 110 kJ/mol. The coating with amorphous structure was more active than the metallic Ni with crystalline structure to react with Al, and the bonding interface between Ni/P-coating and Al-matrix was composed of two layers of single-phase structure, namely Al3Ni and Al3Ni2. The preferred reaction product in the solid-solid compositing process was Al3Ni, and then Al3Ni2 was formed between the Ni layer and Al3Ni layer because of the accumulation of Ni atoms. While, the preferred reaction product in the solid-liquid compositing process was Al3Ni2, and Al3Ni phase was proved by the pulsed magnet field to be generated during the subsequent solidification process.