Alkaline earth Cycio-hexaphosphates were prepared by wet chemical processes. All these Cycio-hexaphosphates contained water of crystallization. When the Cycio-hexaphosphates were heated, the following thermal changes were obsereved.
Dehydration
M₃ (PO₃) ₆·nH₂O→M₃ (PO₃) ₆· (n-x) H₂O+xH₂O
Hydrolysis nM₃ (PO₃) ₆+3H₂O→3M_nH₂P_2nO_6n+1
Condensation
M_nH₂P_2nO_6n+1→ [M (PO₃) ₂] _n+H₂O
Where M stands for alkaline earth metals. The final thermal products above 500 to 600°C were metaphosphates and one can write the overall reaction for the changes :
nM₃ (PO₃) ₆·nH₂O→3M_n (PO₃) _2n+nH₂O

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Experiments were carried out using the carbonated tobermorites prepared by treating tobermorites slurry with CO₂ gas in the several conditions. Results were as follows :
(1) In the case of sample No.2 carbonated to 2%, 55% of tobermorite changed to silica gel by treating No. 2 with acid solution. Sample No. 5 having 53% carbonation ratio was composed of vaterite phase. Sample No. 6 having 96% carbonation ratio was compose of calcite phase.
(2) Tobermorite crystal collapsed treating uncarbonated No. 1 with pH2 solution and it was difficult to separate the solid phase from this solution mixture. In the case of sample No. 5 and No. 6, large amount of CaO content was solved out by the same treatment. But solved amount of silica content was very small and its crystal shape did not change and the solid phase was easily separated from the solution mixture.
(3) Sample No. 1 and No. 6 did not have the immobilization property to Cd²⁺ ion. Sample No.5 had the immobilization property to Cd²⁺ ion and Cd²⁺ ion was precipitated as CdCO₃. Cd²⁺ ion was almost removed from solution, not relating to the kind of negative ion contained in Cd²⁺ ion solution.

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This paper presents experimental results of an attempt at developing xonotlite composites reinforced with polymeric short fibers. Emphasis has been placed on the development of design methodology for toughening the brittle matrix by multiple cracking phenomenon. The composite parameters examined in this study were fiber volume fraction, fiber dimensions, matrix properties and interface shear strength, and their effects on the strength and fracture energy of the composites were studied using five types of polymeric fibers. Low-temperature-plasma treatment and glass coating treatment were employed to modify interface properties. It is demonstrated that multiple cracking is useful to create pseudo-strain hardening behavior and to enhance both the strength and fracture energy. The maximum strength and fracture energy of the composite are shown to be higher than those of the plain matrix by factors of about 10 and 650, respectively. Based on the experimental results, a design diagram for pseudo-strain hardening induced by multiple cracking is proposed.

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Wollastonite-Spdumene composite ceramics has high thermal shock resistance. However, mechanical properties of wollastonite-spodumene, such as fracture strength and fracture toughness, are relatively low compared with conventional ceramics.
In this study, improvment of mechanical properties of wollastonite-spodumene was conducted based on tetragonal-ZrO₂ particles dispersion. ZrO₂ dispersing results in at least two-fourfold increase in the fracture toughness of non-dispersed composites.

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Fusion of ground natural quartz powder was carried out in propane-oxygen flames. The flow rates of propane and oxygen gases and powder feed rate were varied from 5 to 12.5 and from 25 to 62.5 Nm³/h and from 3 to 50 kg/h, respectively, but the flow rate of oxygen carrier gas at 7.5 Nm³/h was kept constant. Two types of burners were used, where a powder-feeding nozzle was placed axially at the center of burner and six nozzles were around the center of another type of burner. The vitrification ratio of about 80% was observed when the powder was treated at the condition of the gas flow rates of 5 for propane gas and 25 Nm³/h for oxygen gas, and the feed rate of powder at 20 kg/h. Small particles showed higher vitrification ratio and sphericity than large one. It was also found that high vitrification ratio was obtained using the burner with six nozzles. Small particles with some hundreds of nm in size which are generated in the flame contribute to an increase of specific surface area of products.

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Pyroaurite-like compounds in the systems of Mg, Fe-NO₃ and Mg, Fe-SO₄ have been prepared under the hydrothermal condition and their Cl-derivatives have been also obtained by the ion exchange of these pyroaurite-like compounds with Cl- ion in saturated NaCl solution. The ion exchange characteristics of these Cl-derivatives for NO₃^- or SO₄^2- ion which was included in the interlayer space of the original pyroaurite-like compounds are compared with those of a pyroaurite-like compound in the system of Mg, Fe-Cl. The ion exchange reactions with NO₃^-are exothermic and the reaction heat for the Cl-derivative of NO₃^--form is larger than that for the Cl-form. The Cl-derivative of NO₃^--form has exhibited high selectivity for NO₃- ion and is possessed of the ion memory effect. On the other hand, the ion exchange reactions with SO₄^2- are endothermic and the exchaved ratios are rather low.

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