a b s t r a c tZirconia sphere particles were synthesized through the gelation process of Na-alginate, and cermet (ZrO 2 -Mo) pellets were fabricated under several conditions. In this process, a zirconia slurry was prepared by mixing oxide powders (ZrO 2 , Y 2 O 3 , Er 2 O 3 , CeO 2 ), distilled water and Na-alginate, and subsequently dropped into CaCl 2 solution. As a result, zirconia sphere particles coated with a gelled film were synthesized. The slurry density (zirconia content in slurry) of 30-64 wt.% and Na-alginate concentration of a few% were good for gelation for up to 10 wt.% CaCl 2 solution. Sphere particles with smaller diameter were obtained by dropping slurry with a mechanical vibration. The prolongation of the ball milling time for mixture of oxide powders was effective to increase the sintered density of zirconia sphere particles, especially for higher CeO 2 concentration. The dense cermet pellets were fabricated for max. 50% volume ratio of zirconia phase for Mo matrix using zirconia particles covered with Mo powder by a rotating granulation method.
Traditionally, the metal mouthpieces of trumpets have been generally made of brass. However, for musicians who suffer from metal allergies, the use of the mouthpiece sometimes lead to inflammation of the lip if they are taking part in a long performance. This problem can be solved by using allergy-free pure titanium (titanium) and its alloys as the material for the mouthpiece. Therefore, a titanium alloy composed of non-toxic and allergy free elements has been designed. However, because their heat conductivity is generally poor, and they contain phase with its HCP (hexagonal closed packed structure having structure, which restrict slip systems, forming them into suitable shapes can be very difficult. Therefore, precision casting method, where only final finishing was conducted by machining, applied for fabricating the mouthpieces of trumpets.Important considerations for use in musical instruments are the material characteristics and the sound characteristics of mouthpieces made of titanium alloy. Research on the material characteristics of titanium alloy mouthpieces is currently being undertaken. On the other hand, the sound characteristics of mouthpieces made of titanium alloy have not been examined sufficiently. In this study, the sound and the vibration characteristics of two kinds of mouthpieces made of titanium and Ti-Nb was examined. The adaptability of these materials for use in mouthpieces of trumpets was discussed by comparing the sound characteristics of mouthpieces of trumpets made of titanium, Ti-Nb, and brass.
Binary titanium alloys containing Nb or Ta, which are allergy-free and non-toxicity elements, were fabricated, and then the possibility of their application to various music instruments made of brass was investigated by the evaluation of corrosion characteristics, elastic modulus-density ratio E/r , resonance frequency f and internal friction Q Ϫ1. The practical models of the mouthpieces of the trumpets made of the binary titanium alloys were also fabricated by precision casting method in order to compare directly with the sound characteristics of those made of brass and commercially pure Ti. The critical current density for the passivation of the Ti-Nb and Ti-Ta system alloys is approximately 40% lower than that of brass and nearly equal to or a little higher than that of commercially pure Ti. The Q Ϫ1 of the Ti-Nb and Ti-Ta system alloys with a Љ phase drastically increase. The E/r and f of the Ti-Nb and Ti-Ta system alloys exhibit a positive relationship. The sound characteristics of practical mouthpieces of trumpets for a bass instrument can be controlled by changing the E/r and f of the alloys.
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