As a result, the content and distribution of the liquid phase became suitable for complete densification, which resulted in density increase. The specimens made with fine powders shows high density because of the melting of the secondary oxynitride phase. The specimens prepared by using coarse powders did not show high density at high-temperature gas-pressure sintering, because of the abnormal growth of elongated β-Si 3N 4 grains owing to the insufficiency and the inhomogeneous distribution of the liquid phase. Different secondary phases were formed in each specimen reaction-sintered with different particle sizes due to the content difference in native oxide on the surface layer of particles. The effect of raw-Si particle size on the properties of sintered reaction-bonded silicon nitride (sintered RBSN) was investigated by the use of Si powders with different particle sizes containing various native SiO 2 oxide contents. This was explained by the exothermic nature of the reaction between Si and N 2 and the fact that small samples with a large surface-to-volume ratio attain thermal equilibrium with their environment better than large samples which may be subject to local overheating. Within the investigated range of sample dimensions (0.2–4.0 g) the unexpected observation was made, that with decreasing sample weight the nitridation rate also decreased. By varying the added amounts of the sintering aids, it was found that increasing the Y 2O 3 and MgO contents both improved the nitridation rate, whereas an increase of Al 2O 3 content resulted in reduced nitridation rates. For the processing of micro-components it was of special interest to study, how a decreasing sample size and wall thickness would influence the rate of Si 3N 4 formation. One question to be answered was how the sintering aids affect the nitridation behaviour of a silicon green body. It does not store any personal data.In order to establish a process for the manufacturing of injection moulded micro-components of sintered reaction-bonded silicon nitride (SRBSN) several process parameters were investigated with regard to their influence on the reaction-bonding step. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The cookie is used to store the user consent for the cookies in the category "Performance". This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other. The cookies is used to store the user consent for the cookies in the category "Necessary". The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". The cookie is used to store the user consent for the cookies in the category "Analytics". These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly. Esta propiedad, en combinación con sus propiedades térmicas, convierte al SiC en un sustituto prometedor de los semiconductores tradicionales como el silicio en aplicaciones de alta temperatura. También se clasifica como un semiconductor, que tiene una conductividad eléctrica entre la de los metales y los materiales aislantes. Su alta conductividad térmica, junto con su resistencia a altas temperaturas, baja expansión térmica y resistencia a la reacción química, hace que el carburo de silicio sea valioso en la fabricación de ladrillos de alta temperatura y otros refractarios. Además de la dureza, los cristales de carburo de silicio tienen características de fractura que los hacen extremadamente útiles en muelas abrasivas y en productos de papel y tela abrasivos. Tiene una calificación de dureza Mohs de 9, acercándose a la del diamante. Hasta la invención del carburo de boro en 1929, el carburo de silicio era el material sintético más duro conocido. Ofrecemos toda la gama de productos (barras, rodillos, soportes, etc.) para hornos eléctricos o de gas. Fundas para termopares y piezas con alta resistencia al choque térmico en diferentes variedades de nitruro de silicio (Si3N4). Toberas, quemadores y tubos radiantes en diferentes materiales de carburo de silicio (SiC, SiSiC, RSiC) para hornos de llama directa (combustión) ó indirecta (convección ó radiación).
0 Comments
Leave a Reply. |