Twin-screw extrusion synthesis of low-cost cobalt ferrite ceramic pigments using natural mixed-dimensional palygorskite clay

Due to the disadvantages of traditional solid-phase and liquid-phase methods for preparation of mixed metal oxide ceramic pigments, it is indispensable to develop a green, clean, low-cost and continuous preparation technology. In this study, the low-cost and high-performance cobalt ferrite ceramic pigments were facilely prepared based on natural mixed-dimensional palygorskite clay by a continuous mechanochemical method using twin-screw extrusion. The incorporation of the mixed-dimensional palygorskite clay effectively improved the agglomeration of pigment nanoparticles and decreased the production cost. The hybrid pigments presented the optimal color properties (L* = 17.16, a* = 1.07, b* = 3.58 and C* = 3.74) when the cobalt ferrite content, calcination temperature and time were 60 wt%, 1100 °C and 90 min, respectively. Furthermore, the as-prepared hybrid pigments exhibited excellent chemical and thermal stability and biocompatibility, the mass tone and hiding power of the hybrid pigments were superior to the commercial cobalt black pigments, thus the obtained hybrid pigments could be served as an eco-friendly underglaze pigment for coloring of ceramic embryo body with good color saturation. Beyond all doubt, this study will provide a promising strategy for continuous cleaner preparation of low-cost cobalt ferrite ceramic pigments.