Effect of CeO₂ Addition on Microstructure and Friction and Wear Properties ofBoronizing Layer on Surface of Iron-Based Powder Metallurgy Materials

Fe-2%Cu-0.4%C iron-based powder metallurgy material was boronized at 950 ℃ for 5 h by solid powder boronizing method with a boronizing agent containing CeO₂. The effects of CeO₂ addition (0,2%, 4%, mass fraction) on the microstructure and friction and wear properties of the boronizing layer were studied. The results show that the boronizing layer with different addition amounts of CeO₂ had a single Fe₂B phase. With the increase of CeO₂ addition, the surface roughness of the boronizing layer increased, and the thickness, hardness and wear resistance increased first and then decreased. When the mass fraction of CeO₂ was 2%, the thickness and hardness of the boronizing layer were the largest, about 144 μm and 58.0 HRC, respectively. At this time, the surface integrity of the boronizing layer was relatively good, the amount of wear was the smallest, about 0.008 g, and the wear resistance was the best.