Table 2.
Use of halloysite in advanced ceramic products.
| Origin of Halloysite | Starting Raw Materials | Synthesis | Processing | Ceramic Product | Ref. |
|---|---|---|---|---|---|
| Not provided | Kaolinite-rich clay, halloysite-rich lay, carbon | Carbothermal method and nitridation method | Firing of starting mixtures at 1800 °C for short periods | SiAlON | Lee et al. (1976) |
| China | Halloysite-rich clay or kaolinite-rich clay, carbon | Carbothermal reduction and nitridation method | Starting mixtures milled in hexane for 17 h and fired at 1400 °C for times 10 min to 24 h | β’-SiALON | MacKenzie et al. (1994) |
| New Zealand | Halloysite-rich clay, carbon | Carbothermal reduction and nitridation method | Firing of starting mixtures at 1400 °C for 1–480 min | β-SiAlON | Neal et al. (1994) |
| China | Halloysite-rich clay, carbon, silica or elemental Si ± Y2O3 | Carbothermal reduction and nitridation method |
Starting mixtures milled for 24 h in ethanol and fired at 1000–1400 °C for 2 h | low-z β’-SiAlON | MacKenzie et al. (1997) |
| New Zealand | Halloysite-rich clay, carbon, silica or elemental Si, Y2O3 | Carbothermal reduction and nitridation method | Starting mixtures milled in ethanol for 4 h and fired at 1475 °C for 8 h, (a-SiAlON powders)/α-SiAlON powders were pelletized and hot pressed at 1800 °C for 2 h (dense α-SiAlON ceramics) | a-SiAlON | Ekstrom et al. (1998) |
| China | Halloysite-rich clay, alumina, elemental Si, metal oxides additives | Silicothermal method and nitridation method | Starting mixtures milled for 20 h in hexane using Si3N4 media and fired at 1200–1500 °C, with the remaining 4 h at the maximum temperature | X-SiAlON | Sheppard and MacKenzie (1999) |
| New Zealand | Halloysite-rich clay, talc, carbon black± 3 wt%α-Si3N4 | Carbothermal reduction and nitridation method | Starting mixture milled in ethanol for 24 h and fired at 1450–1500 °C in nitrogen gas for 2–16 h | Mg-αSiAlON | Qiu et al. (2002) |
| New Zealand | Halloysite-rich clay, fine carbon | Carbothermal reduction and nitridation method | Starting mixture ground for various periods and heated at 1200–1400 °C for 12 h | β-SiAlON | MacKenzie et al. (2006) |
| Not provided | Halloysite-rich clay, Si, AlN | Silicothermal reduction and nitridation method | Sintering of starting prepared mixtures at maximum temperature of 1250–1500 °C for 3 h | β-SiAlON | Yin and Jones (2017) |