Effect of pyrochemical chloride waste loading on thermo-physical properties of borosilicate glass bonded Sr-chloroapatite composites

• Published in: Materials chemistry and physics 2015-07, Vol.162, p.188-196
• Main Authors: Jena, Hrudananda, Maji, Binoy Kumar, Asuvathraman, R., Kutty, K.V.Govindan
• Format: Article
• Language: English
• Subjects: Chemical synthesis; Composite material; Glass-transition; Inorganic compounds; Thermal expansion; Xray-scattering
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2015.05.057

Borosilicate glass (BSG) bonded composites of Sr-chloroapatite (SrApCl) and its simulated pyrochemical waste loaded compositions were synthesized by solid state reaction route. These compositions were characterized by XRD and SEM. Percentage (%) thermal expansion of the composites was measured by high temperature XRD (HT-XRD) and dilatometry. 10–16 wt.% waste loaded composites show minor variations in % linear expansion at 298–900 K. The composite with 10 wt.% waste loading and without BSG encapsulation exhibited slightly higher % of expansion compared to other compositions above 700 K. The coefficient of thermal expansion (αm) measured by HTXRD and dilatometry are found to be of the same order of magnitude. The % expansion measured by dilatometry shows higher values for waste loaded compositions compared to SrApCl; whereas values measured by HTXRD show a decreasing trend with respect to pristine SrApCl. The instantaneous coefficient of thermal expansion (αi) is used to determine the glass transition temperature (Tg) of the glass-bonded composites from the dilatometry data. The αi measured by HTXRD for the composites ranges from 2.40(1) × 10−7 to 9.51(2) × 10−6 K−1 along a-axis, 9.28(1) × 10−8 to 7.68(1) × 10−6 K−1 along c-axis and. αm measured by dilatometry ranges from 3.80(1) × 10−7 to 13.14(1) × 10−6 K−1. [Display omitted] •BSG bonded Sr-chloroapatite composite with 10–16 wt.% waste loading was synthesized.•Composites were characterized by HTXRD, SEM-EDAX and dilatometry.•Instantaneous coefficient of thermal expansion (αi) is used to measure Tg.•HTXRD rules out the formation of metastable phases in the host matrix on heating.•% expansion of 10–13 wt.% waste loaded samples are close to the pristine SrApCl.