The future manufacturing for the recirculation-based society needs to take into consideration environmental impact for the earth and functions for people simultaneously. The authors have investigated nature mimetic functional indoor housing materials. In this paper, two examples for saving energy and making comfortable space were introduced. One is anti-stain surface treatments for ceramic tile using hydrophilic nanoparticles, resulting in the decrease of the housekeeping energy. The other are porous ceramic materials to save air conditioning energy, which are the humidity control ceramic tile using mesoporous soil and the vacuum insulation panels using nanoporous silica particles.

In this study, the effect of multivalent ions on ionic crosslinking of polyelectrolytes adsorbed on particle was investigated. Ammonium polycarboxylate, one of the typical polyelectrolytes, was used as a dispersant. Zinc oxide and titanium oxide was used as sample powder. A well-dispersed slurry was prepared by adding polyelectrolytes as the dispersant beforehand. Thereafter, multivalent cations were added to the slurry to convert it from liquid to a gel-like consistency, which was caused by the ionic crosslinking of polyelectrolytes adsorbing on the surface of the particles. It was found that the ionic radius of adding multivalent cation has an influence on the strength of the gel. It was also shown that this method was effective for prevention of density segregation during sedimentation.

Herein we report a new grinding method to obtain fine particles having high specific surface area which is difficult to realize a conventional dry grinding. Several inorganic carbonates and metal oxides have been studied. Planetary ball milling under dry conditions and subsequent water addition realize the particles with a crystallite size and equivalent size of the specific surface area in the nanometer range. The equivalent size could be down to 25–136 nm using our method except TiO₂. Regarding ground TiO₂ sample, 47 nm in the equivalent size was successfully obtained via adding KOH solution and washing process. From the view point of solubility, we proposed the mechanism for the equivalent size down to nanometer range.

Titania coated silica hollow particles were developed as a white pigment to prevent their sedimentation during storage. The hollow silica particles used in this study have porous structure, which is expected to have both scatter and transmit visible light to help to improve the titania’s covering power. The template for such porous structure was prepared by gathering nano-sized calcium carbonate via CO₂ gas bubbling method. For the titania coating, acetic acid was used to control too quick chemical reaction of titania precursor by forming chelate compound. The molar ratios of water/titania and reaction temperature were optimized. The obtained titania coated hollow silica particles exhibited higher whiteness than the commercial TiO₂.

Two kinds of powder mixtures, amorphous silica-gibbsite [Al(OH)₃-SiO₂] and amorphous silica-alumina (Al₂O₃-SiO₂), were ground using a planetary ball mill under dry and wet (with water) conditions to investigate the the mechanochmical phenomena on the formation of mullite (3Al₂O₃·2SiO₂) in sintered powders. The dry grinding showed the significant mechanochemical effects due to the XRD patterns and immersion heat data in comparison with the water wet-grinding, while the water wet-grinding enabled the well-dispersed and lower size powders to be prepared. The degree of mullite phase formation after the sintering depended on the amorphousness of the ground mixture of the raw material. Adequately considering the merits of dry and wet grindings, 90 minute dry grinding followed by 30 minute water wet-grinding resulted in higher degree of mullite phase formation after the sintering than the powders prepared through the both 120 minute dry and wet grinding.

In this paper, three types of precursor powders with nominal composition of 3Al₂O₃·2SiO₂ (stoichiometric composition) were prepared from tetra-methyl ortho-silicate (TMOS) and aluminum i-propoxide or aluminum nitrate to investigate the influence of the precursor powders on the sinterability and the mechanical properties of the resulting mullite ceramics. The results showed that compositional homogeneity and the agglomeration state of the precursor powders have large effect on the crystallization behavior and the sinterability, because the amount of the transient SiO₂ phase affected both the sinterability and the crystallization behavior. Precursor powder from TMOS and aluminum nitrate resulted in the lower sinterebility and the lower mechanical properties of the resulting mullite ceramics. On the other hand, mullite ceramics sintered from alkoxide-derived precursor powders exhibited relatively higher mechanical properties at higher temperatures. Finally, we successfully prepared mullite ceramics with stoichiometric composition and excellent high-temperature mechanical properties by tuning the processing conditions.