Influence of thermal treatment on CTO wettability

[Display omitted] ► We synthesized CTO and its two components: HTO and COD. ► The wettability of these samples with silicon oil was examined and compared. ► The wettability of CTO and HTO decreases with increasing heating temperature. ► The oxalate in HTO, as well as CTO, decomposed during the heating process. ► We may attribute the change in CTO wettability to the decomposition of the oxalate. Calcium–titanium–oxygen precipitate (CTO) is well known for its notable electrorheological performance. The two main components of CTO particle are calcium oxalate dehydrate (COD) and titanium–oxygen precipitates (HTO). We systematically studied the wettability of these three compounds with silicon oil at different thermal treatment temperatures. We found that the wetting performance of the HTO decreases with increasing heating temperature, the same tendency as that of CTO particles. This discovery inferred that the wettability of CTO particles is dominated by HTO component. Thermal gravity analysis, X-ray diffraction, X-ray photoelectron spectroscopy as well as the wettability analysis were applied to demonstrate our proposition. The results revealed that HTO is decomposed into inorganic compounds like free carbon by thermal treatment, resulting in a decrease of the wettability of the CTO particles.