| FANG Yu-lan,LIU Rui-liang,SONG Tian-yu,LIU Ai-dong.Effect of Rare Earths on Microstructure and Properties of Plasma Electrolytic Carburized Layer[J],52(6):61-69, 79 |
| Effect of Rare Earths on Microstructure and Properties of Plasma Electrolytic Carburized Layer |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.06.006 |
| KeyWord:stainless steel plasma electrolytic carburized rare earth microstructure wear resistance |
| Author | Institution |
| FANG Yu-lan |
Key Laboratory of Ultra-Light Materials and Surface Technology of Ministry of Education, School of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin , China |
| LIU Rui-liang |
Key Laboratory of Ultra-Light Materials and Surface Technology of Ministry of Education, School of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin , China |
| SONG Tian-yu |
Key Laboratory of Ultra-Light Materials and Surface Technology of Ministry of Education, School of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin , China |
| LIU Ai-dong |
Key Laboratory of Ultra-Light Materials and Surface Technology of Ministry of Education, School of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin , China |
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| Abstract: |
| To study the effect of rare earths on the microstructure and properties of liquid plasma electrolytic carburized layer, in this paper, the rare earths LaCl3.7H2O and CeCl3.7H2O were added to the electrolyte, and the liquid plasma electrolytic carburized layer with or without rare earths addition was prepared on the surface of 17-4PH stainless steel. The surface morphology, cross-sectional structure and phase structure of the infiltrated layer were analyzed by scanning electron microscope, metallographic microscope and X-ray diffractometer. The hardness, toughness and wear resistance of the infiltrated layer were evaluated by Vickers hardness tester, Rockwell hardness tester and friction and wear tester. The results show that the carburized layer is mainly composed of carbides, expansive “α” phase and a small amount of iron oxides. Both LaCl3.7H2O and CeCl3.7H2O can promote the formation of carbides on the surface of the plasma electrolytic carburized layer, and CeCl3.7H2O can effectively inhibit the formation of iron oxides on the surface of the carburized layer. After adding rare earths LaCl3.7H2O and CeCl3.7H2O, the thickness of the porous compound layer on the surface of the infiltration layer decreased from 20 μm to 15 μm and 8 μm respectively, and the total thickness of the dense layer + diffuse layer increased from 20 μm to 46 μm and 45 μm respectively. The thickness of the infiltration layer increased, the surface roughness decreased and the compactness increased. After adding rare earths LaCl3.7H2O and CeCl3.7H2O, the effective hardened layer thickness of the layer can reach 70 μm, which is more than 3 times that without rare earths, and the cross-section hardness is gradient distribution. After adding rare earths LaCl3.7H2O and CeCl3.7H2O, the radial cracks near the Rockwell indentation on the surface of the carburized layer appeared obvious deflection, which alleviated the decrease of toughness after plasma electrolytic carburizing. The addition of rare earths LaCl3.7H2O can significantly reduce the friction coefficient to 0.14 at the early stage of friction, and the width of wear scar is reduced to 534 μm, which mainly occurs oxidative wear, compound layer spalling and abrasive wear. The addition of rare earths CeCl3.7H2O can maintain the friction coefficient at about 0.21, and the width of wear scar is signi ficantly reduced to 226 μm, which mainly occurs slight abrasive wear. Both rare earths LaCl3.7H2O and CeCl3.7H2O can increase the thickness of the infiltration layer, improve the surface quality of the infiltration layer, and improve the hardness and wear resistance. Among them, the effect of rare earths CeCl3.7H2O on improving the surface quality of the infiltration layer and improving the wear resistance is more significant. |
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