Preparation and characterization of high chemical durability and low thermal expansion borosilicate glass-ceramic composites by recycling of borosilicate glass

Borosilicate glass recycling is a challenge because it has high melting point and different chemical structure which makes it non-recyclable in the glass industry. This work focuses on borosilicate recycling through the preparation of a low thermal expansion and chemically durable borosilicate glass-ceramic composite (BsGC). Low thermal expansion and high chemical durability ceramics are advantageous in many applications such as lab supplies, corning ware, automobile components, and other low expansion products that are resistant to thermal shock. Kaolin and borosilicate were chosen for the preparation of glass-ceramic composite, because they have low thermal expansion and good chemical durability. BsGC was prepared by sintering borosilicate glass waste (e.g., Pyrex laboratory glassware, household glass) and kaolin at different temperatures (750-900 degrees C). Water absorption method was used to measure the apparent porosity of the prepared composites. Surface morphology of the prepared BCGs was investigated using scanning electron microscopy (SEM). Phase composition of the prepared BGC samples was characterized using X-ray diffraction technique (XRD). The XRD results showed that at sintering of 750 degrees C a monocrystalline quartz was only existing. By increasing sintering temperature up to 800 degrees C the quartz phase decreased, while at 850 degrees C the quartz phase completely disappeared. The sintered BCG composites obtained exhibited low coefficients of thermal expansion in the range of 48 x 10-7 degrees C-1 and exhibited high chemical durability.