Ceramic materials are ubiquitous in the construction world. Building materials such as cement, bricks and tiles and electrical insulators such as porcelain are all ceramic products that we rely on in our daily lives. These ceramics are manufactured by a method called sintering – the process of converting powdered solids into a solid mass by means of pressure or temperature. Most sintering processes involve temperatures in excess of 1000°C, which makes this method very energy-hungry. Moreover, the high temperature makes it difficult to sinter raw materials such as carbonates and hydroxides because they are subject to thermal decomposition at high temperatures.
Magnesium carbonate and hydroxides are emerging candidates for building materials due to their thermodynamic stability and ability to harden or sinter, such as slaked plaster. However, these materials cannot be sintered using the conventional sintering process because they undergo thermal decomposition. However, little is known about how these materials react with a milder technique called cold sintering. To address this research gap, a team of researchers from Nagoya Institute of Technology, consisting of Professor Shinobu Hashimoto and Mr. Kitaro Yamaguchi, investigated the mechanism by which Mg-COH systems are hardened by the cold sintering process (or CSP). Their findings are summarized in a recent study made available online on April 21, 2022 and published in International Ceramics On August 1, 2022.
CSP has gained popularity in recent years due to its low energy dependence. This process mimics the process of sedimentary rock formation that occurs in the Earth’s crust, allowing it to solidify under several hundred MPa of pressure but at more moderate temperatures such as 300°C or less. This makes the process less energy consuming and ideal for manufacturing building materials with lower pyrolysis temperatures.
“Basic magnesium carbonate, or magnesite, has been proposed for use as a carbon storage material along with its use as a structural material. But magnesium is difficult to produce by conventional industrial methods due to the effect of water during production and high-temperature pyrolysis of the sintering process,” explains Professor Hashimoto. “Our study aims to understand whether Mg-COH systems can undergo a desirable annealing process in building ceramics via CSP.”
The team used magnesium hydroxide and basic magnesium hydroxide powders as ceramic precursors and water as a solvent. They heated the former at 250°C and the latter at 150°C with 10% mass of water, under a pressure of 270 MPa for 1 hour each. they found it compressive strength The relative density values of hardened magnesium hydroxide were 121 MPa and 84%, respectively, while those of basic, solid magnesium carbonate were 275 MPa and 88%, respectively. The team also discovered that water played an important role in promoting the dissolution and precipitation reaction necessary for the condensation of the powders during CSP. This phenomenon ensured that sintering occurred to form solid blocks at lower temperatures.
The results of this study provide a new perspective on sintering, which is generally considered a high-temperature, high-energy process. CSP not only allows the manufacture of ceramics for materials exposed to it pyrolysis But it also guarantees excellent results by controlling the microstructure of the solid products.
“The construction industry It is one of the largest consumers of energy and is responsible for 38% of energy-related carbon dioxide globally2 emissions. With our research, we aim to get one step closer to building a future where industrialization Building materials More sustainable and greener,” concludes Professor Hashimoto.
Keitaro Yamaguchi et al, Cold sintering of the Mg-COH system, International Ceramics (2022). DOI: 10.1016 / j.ceramint.2022.04.162
Nagoya Institute of Technology
the quote: Mimicry of the Earth’s Crust: Examination of Hardening of Filtered Building Materials by Cold Sintering (2022, Sep 21) Retrieved on Sep 21, 2022 from
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