Effects of Precipitant and pH on Coprecipitation of Nanosized Co-Cr-V Alloy Powders

• Main Authors: Xiaoyu Chen, Yongxia Li, Lan Huang, Dan Zou, Enxi Wu, Yanjun Liu, Yuanyan Xie, Rui Yao, Songyi Liao, Guangrong Wang, Feng Zheng
• Format: Article
• Language: English
• Published: MDPI AG 2017-09-01
• Series: Materials
• Subjects: Co-Cr-V alloy; morphology coarsening; coprecipitation; precursor; nanosize
• Online Access: https://www.mdpi.com/1996-1944/10/10/1108

Nanosized Co-Cr-V alloy powders were synthesized via coprecipitation method. Effects of precipitants ((NH4)2C2O4·H2O and Na2CO3) and pH were investigated by X-ray diffraction (XRD), Zeta potential analyzer, thermogravimetry-differential scanning calorimetry (TG-DSC), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and scanning electron microscopy (SEM). Co-Cr-V alloy powders were consisted of major face-centered cubic Co (fcc Co) and minor hexagonal close-packed Co (hcp Co). Grain sizes of precursors and Co-Cr-V alloy powders were increased with pH value (7–10) within the ranges of 3~39 and 39~66 nm, respectively. Rod-like or granular Co-Cr-V alloy particles were assembled by interconnected nanograins. At pH = 7, Na2CO3 precipitant was found to be beneficial to maintain the desirable composition of Co-Cr-V powders. It was also found that lower pH favors the maintenance of pre-designed composition, while grain coarsens at higher pH. Effects of variation for precipitant and pH on the morphology and composition of Co-Cr-V alloy powder were discussed in detail and relevant mechanism was further proposed.