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22 results on '"Hong, Dongbo"'

21. Microwave synthesis of duplex α/β-SiAlON ceramic cutting inserts: Modifying m, n, zvalues, synthesis temperature, and excess Y2O3synthesis additive

Author

Hong, Dongbo, Yin, Zengbin, Guo, Fuzhou, and Yuan, Juntang

Abstract

Duplex α/β-SiAlON ceramic cutting inserts (30α:70β) were synthesized by microwave sintering. The effects of solid solution parameters (m, n, z), synthesis temperature, and amount of excess Y2O3synthesis additive on phase assemblage, microstructure, mechanical properties, and cutting performance were systematically investigated. It was found that increasing mvalue could improve the formation of α phase while high zvalue over 1.0 resulted in the dissolution of α phase into β phase and intergranular phase. Increasing the amount of excess Y2O3could promote densification and elongated β grain growth; however, the excess Y2O3amount above 4 wt% resulted in substantial crystallization of M’SSphase, thus declining the mechanical properties and wear resistance. The microwave-synthesized α/β-SiAlON cutting insert with modified parameters (m= 1.7, n= 1.0, z= 0.7, and 3 wt% excess Y2O3) was obtained with optimal comprehensive properties, whose tool life was found to increase by approximately 75% in high-speed milling of Inconel 718 superalloy compared to the commercial α/β-SiAlON cutting insert.

Published
2022
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22. Effects of metal phases on microstructure and mechanical properties of microwave‐sintered Ti(C, N)‐based cermet tool.

Author

Ye, Jiadong, Yin, Zengbin, Yuan, Juntang, Li, Zhiyuan, Zhu, Zhiyong, and Hong, Dongbo

Subjects
METAL microstructure, FRACTURE toughness, SPECIFIC gravity, TITANIUM powder, HARDNESS, MICROWAVE sintering, MICROSTRUCTURE
Abstract

A kind of Ti(C, N)‐based cermet tool material was prepared by microwave sintering. The influence of metal phases (Ni, Co, and Mo) on densification and mechanical properties was studied by orthogonal test. The results indicated that Co was more significant in improving relative density and fracture toughness than Ni, while Ni and Co had the similar effects on increasing the hardness of Ti(C, N)‐based cermet. Mo can improve fracture toughness but decrease hardness. Ti(C, N)‐based cermet with 6 wt% Ni, 6 wt% Co and 6 wt% Mo (TN6C6M6) had the optimal comprehensive mechanical performances, and its fracture toughness and hardness were better than that of Ti(C, N)‐based cermet prepared by conventional sintering. The increasing of sintering temperature promoted the uniformity of microstructure and significantly improved densification and hardness of the Ti(C, N)‐based cermet. The highest fracture toughness of TN6C6M6 (12.41 ± 0.33 MPa·m1/2) was achieved when sintered at 1600°C. For the microwave‐sintered Ti(C, N)‐based cermet, heat preservation period had little effect on densification. The relative density can reach up to 98.6% even though the heat preservation period was 0 minute. [ABSTRACT FROM AUTHOR]

Published
2020
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