The devitrification kinetics of transparent silica glass prepared by gel-casting method

Abstract

The kinetics of the crystallization of cristobalite in the amorphous silica glass were studied for samples prepared by gel-casting and sintering in air. Avrami and rate equations were used to calculate the rate constants and the activation energy. The results showed that the crystallization obeys the first order and occurs mainly on the surface with activation energy of 543-546kJ/mol. The fewer amounts of OH-groups and the high amount of oxygen vacancies are expected to stand behind the increase in the activation energy as compared with that reported in literatures.

Rapid Pressureless Sintering of Glasses

“…As shown in Figure 1b; and Figure S2, Supporting Information, the white pellet became translucent after CIP (40 MPa, 40 s), and then turned fully transparent and uniform after the UHS process. The UHS method can achieve 1-3 orders of magnitude faster sintering (Figure 1c) compared to other techniques such as gel-casting and sintering, [12] conventional furnace sintering, [10,11,32,33] SPS, [13][14][15][16] laser sintering, [22] and FS. [20] Compared with other sintering methods, our UHS technique has multiple advantages for glass fabrication.…”

“…Conventional solid‐state sintering can reduce the processing temperature but requires hours‐long thermal treatment to obtain dense silica glasses. [ 10,11 ] It was reported that silica glass with a transmittance of ≈83% could be synthesized by gel‐casting and sintering, in which the sintering temperature was reduced to 1373 K; however, the sintering time was still as long as 3 h. [ 12 ]…”

“…Conventional solid-state sintering can reduce the processing temperature but requires hourslong thermal treatment to obtain dense silica glasses. [10,11] It was reported that silica glass with a transmittance of ≈83% could be synthesized by gel-casting and sintering, in which the sintering temperature was reduced to 1373 K; however, the sintering time was still as long as 3 h. [12] Recent studies have demonstrated new methods to synthesize silica glass, such as spark plasma sintering (SPS), flash sintering (FS), and laser sintering. SPS, also known as a field-assisted sintering technology, can obtain dense glasses with a short sintering time (e.g., 2-10 min) and a low-temperature range (e.g., 1073-1883 K).…”

Preparation of transparent Bi2O3‐ZnO‐B2O3 glass by conventional sintering at low temperatures

“…In the literature, the glass compositions that can achieve transparent glass components using the sintering method are mostly pure SiO 2 or predominantly composed of SiO 2 . [19][20][21][22][23][24][25][26][27][28][29][30][31][32] This is because silicate glasses usually have high glass transition temperature (T g ), excellent thermal stability, and are less prone to crystallization during sintering. On the other hand, there is limited literature on the preparation of transparent glasses of low T g by sintering method.…”

Effects of controlled burn rice husk ash on geotechnical properties of the soil

“…On the other hand, amorphous silica is the best for pozzolanic reaction, formed by the controlled temperature at 600°C-700°C (Hwang and Chandra, 1996). The amorphous silica of well-burnt RHA in single-phase displayed a halo pattern with a peak at around 2θ = 22°by the X-ray diffraction (XRD) test (Chandrasekhar et al, 2003;Al-Hasnawi and Al-Hydary, 2019;Nahar et al, 2021).…”