Download or read book Development and Evaluation of Die and Container Materials Third Quarterly Progress Report April 1 June 30 1978 For Molten Silicon written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Methods of producing low-cost silicon sheet for solar cells are under active development. In the crystal-growing processes a refractory crucible is required to hold the molten silicon, while in the ribbon processes an additional refractory shaping die is needed to enable silicon ribbon to be produced. In several ribbon processes the high-temperature materials are a limiting factor in the development of the technique. The objective of this study is to develop and evaluate refractory die and container materials. Mass spectrometric studies of molten silicon in contact with silicon nitride and silicon carbide show that the vapor pressure of silicon is lower over these materials than over the oxides (beryllium oxide, alumina, and silica) studied previously. Measured carbon and nitrogen contents are 6.4 x 1019 atoms/cm3 and 3.3 x 1018 atoms/cm3, respectively. The fabrication of O' and .beta.' Sialons was found to be strongly dependent upon the nature of the silicon nitride powder. A modified hot pressing procedure was adopted to allow volatilization of chlorine-containing species from the SN402 grade powder. .beta.' Sialon of composition X = 1 appears to offer some promise as a candidate die material, but materials containing a higher alumina composition (X = 2.4 Sialon) or the phase known as X phase with molten silicon. O' Sialons of compositions X = 0.1, X = 0.2, and X = 0.35 reacted with molten silicon, forming a complex interface zone. The concentration of thin precipitates in the silicon increased with the alumina content of the O' Sialon solid solution.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1981 with total page 1740 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solar Energy Update written by and published by . This book was released on 1978 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and evaluation of die and container materials written by Battelle Memorial Institute. Columbus Laboratories and published by . This book was released on 1978 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Evalustion of Die and Container Materials Fourth Quarterly Progress Report July 1 September 30 1978 written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mass spectrometric studies of molten silicon in contact with mullite and x = 0.75 .beta.' Sialon show that the vapor pressures of Si, Si0, Al, and Al20 species are very similar. In both cases the oxygen solubility is extremely low, but the aluminium content of the silicon is higher for the mullite--silicon system (3 weight percent), compared with 5000 ppm for the x = 0.75 .beta.' Sialon. The nitrogen concentration (312 ppm) of the silicon is marginally below that for the Si3N4--silicon system indicating that the addition of aluminium and oxygen to .beta. Si3N4 does stabilize the nitrogen to some extent. Silicon beryllium oxynitrides were fabricated by hot pressing Si3N4--BeO-SiO2 mixtures using three Si3N4 powders. Single phase materials were obtained with KBI, Inc. and Sylvania SN502 grade powders, but not with Sylvania SN402 grade powder. Preliminary evaluation of the silicon beryllium oxynitride materials with molten silicon did not reveal any attack of these materials. X = 0.75 .beta.' Sialon did, however, undergo slight attack. It is suggested that the rate of dissolution of aluminium in molten silicon could be affected by whether the Sialon is used in an inert atmosphere or under vacuum conditions.
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 932 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Evaluation of Die and Container Materials written by Battelle Memorial Institute. Columbus Laboratories and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study Program to Develop and Evaluate Die and Container Materials Second Quarterly Report January March 1978 For Liquid Silicon written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The goals of the present program are to develop successful die and container materials for handling liquid silicon while it is being formed into photovoltaic cell material. These goals will hopefully be accomplished by exploring various materials configurations for their reactivity with molten silicon. The combination of unique coating structures combined with control of oxygen partial pressures may yield some previously unsuspected set of conditions which are useful for cost effective die growth or containing silicon melts. Successful experimental configurations will be scaled up into prototype dies and containers as appropriate during the third and fourth quarters of calendar 1978. Economics for large scale production of such prototypes will be defined as part of the program. Die and container material development efforts under the current program are shared among three organizations. Miami Research Laboratories (MRL)--Ceramic process development and overall program management, University of Missouri-Rolla (UMR) (Prof. P.D. Ownby)--silicon sessile drop studies with characterization of reaction products and emphasis on atmospheric effects, Chemetal Corp., Pacoima, Calif. (R. Holzl, president)--special coatings to be applied to test coupons, die shapes and containers provided by MRL and tested/characterized by UMR. MRL has hot pressed three different substrate materials for coating at Chemetal Corp. Chemetal has coated these substrates, and they in turn have been furnished to UMR for sessile drop experiments. UMR has completed assembly of its sessile drop apparatus and has begun sessile drop experiments in order to establish proper techniques and to check out operation of the assembly. Initial experiments were done with Al2O3 and SiO2 substrates, but SiC coated substrates were begun near the end of March.
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II LSSA Project written by M. T. Duffy and published by . This book was released on 1978 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II LSSA Project written by M. T. Duffy and published by . This book was released on 1977 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study Program to Develop and Evaluate Die and Container Materials for the Growth of Silicon Ribbons Quarterly Report written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Die and container material development efforts under the current program are shared among three organizations: Miami Research Laboratories (MRL) - ceramic process development and overall program management; University of missouri-Rolla (UMR) - silicon sessile drop studies with characterization of reaction products and emphasis on atmospheric effects; and Chemetal Corporation, Pacoima, California - special coatings to be applied to test coupons, die shapes, and containers provided by MRL and tested/characterized by UMR. The completion of a major hardware delivery milestone was accomplished with the delivery of three CNTD Si3N4 coated hot pressed Si3N4 crucibles to JPL. A limited characterization of the coating was performed at MRL prior to delivery. The coatings were fine grained .cap alpha. - Si3N4. It has been determined that a two piece die design will be required. At UMR the importance of the role of oxygen in influencing the attack of the CNTD materials by molten silicon has been demonstrated. The stability is greatly enhanced by maintaining the oxygen partial pressure near or below the Si + O2 = SiO2 equilibrium.
Download or read book Development and evaluation of die materials for use in the growth of silicon ribbons by the inverted ribbon growth process task II LSSA project written by RCA Laboratories and published by . This book was released on 1978 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Evaluation of Die and Container Materials written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: X = 0.75?' (a silicon aluminum oxynitride) and Sibeon (silicon beryllium oxynitride) are promising die materials. In sessile drop tests in contact with molten silicon, beryllium contamination was
Download or read book Study Program to Develop and Evaluate Die and Cntainer Materials for the Growth of Silicon Ribbons Quarterly Report written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Die and container material development efforts under the current program are shared among three organizations. Miami Research Laboratories (MRL)--ceramic process development and overall program management, University of Missouri--Rolla (UMR)--silicon sessile drop studies with characterization of reaction products and emphasis on atmospheric effects, Chemetal Corporation, Pacoima, California--special coatings to be applied to test coupons, die shapes and containers provided by MRL and tested/characterized by UMR. Initial sessile drop experiments on SiC, Si3N4 and AlN have been conducted. Very promising results have been achieved on both SiC and Si3N4 where minimal penetration of these (Controlled Nucleation by Thermochemical Decomposition) CNTD coatings by molten silicon was observed. Efforts continued in the following areas. At MRL, a set of AlN and another set of Si3N4 substrates have been hot pressed. Hot pressing experiments have begun on crucible shapes. Characterization efforts have also begun on coatings and substrates. Chemetal delivered AlN coated substrates and began development efforts to produce Si-O-N coatings as predecessor to Si-O-Al-N coatings. UMR has succeeded in measuring the lowest oxygen partial pressures measured, to the knowledge of the investigators, with a solid electrolyte cell on a dynamic flowing gas buffer system. This was achieved with a yttria doped thoria oxygen sensor cell. Even lower pressures beyond this measurement capability have been achieved.
Download or read book Study Program to Develop and Evaluate Die and Container Materials for the Growth of Silicon Ribbons written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Large Area Silicon Sheet Growth Task objective of lowering the cost of silicon photovoltaic material requires the development of materials which exhibit improved chemical and dimensional stability in contact with molten silicon. These materials may find application as containers and/or shaping dies in processes such as edge-defined film growth. The development and evaluation of proprietary coatings of pure silicon carbide, silicon nitride and aluminum nitride on less pure hot pressed substrates of the respective ceramic materials are described. Silicon sessile drop experiments were performed on coated test specimens under controlled oxygen partial pressures. X-ray diffraction and SEM Characterization was performed prior to testing. The reaction interfaces were characterized after testing with optical and scanning electron microscopy and Auger electron spectroscopy. Increasing the oxygen partial pressure was found to increase the molten silicon contact angle, apparently because adsorbed oxygen lowers the solid-vapor interfacial free energy. Adsorbed oxygen was also found to increase the degree of attack of molten silicon upon the chemical vapor deposited coatings. Prototypic containers and dies were delivered and cost projections show that reasonably priced, coated, molten silicon resistant refractory material shapes are obtainable.
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II LSSA Project Quarterly Report No 5 October 1 December 31 1978 written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Several ribbon growth experiments were performed in the Mark II ribbon growth facility from V-shaped dies coated with CVD Si3N4. The most significant result was the ability to perform five consecutive growth runs from the same die without mechanical degradation of the die through temperature cycling. The die was made from vitreous carbon coated with CVD Si3N4. Silicon oxynitride, Si2N2O, was examined with respect to thermal stability in contact with molten silicon. The results of x-ray analysis indicate that this material is converted to both .cap alpha.- and .beta.-Si3N4 in the presence of molten silicon. The latter phase is the dominant phase. Experiments on the stability of CVD SiO3 /sub y/ show that this material can be maintained in contact with molten silicon (sessile drop test) for greater than 30 h at 1450°C without total decomposition. These layers are converted mainly to .beta.-Si3N4. The fabrication of coated EFG-type dies is proving difficult because of thermal expansion mismatch between layer and substrate and instability of substrate materials at high temperature. Self-supporting CVD dies have been prepared on silicon substrates but the wall thickness is not greater than about 50 .mu.m. Experiments are continuing.
Download or read book Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process Task II written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of emission spectroscopic analysis indicate that molten silicon (sessile drop) can remain in contact with hot-pressed Si3N4 (99.2% theoretical density) for prolonged periods without attaining the impurity content level of the nitride. It is interesting to note that, although MgO was used as binder (approx. 3.8%), Mg was not found present in the silicon sessile drop in quantities much above the level initially present in the silicon source material. The conversion of CVD silicon oxynitride to .beta.-Si3N4 can be carried out at high temperature in N2 (approx. 1600°C), by contact with molten silicon or by a combination of these steps. Conversion in the presence of molten silicon appears preferable. Preliminary experiments with EFG-type dies coated with CVD Si3N4 or CVD SiO3 /sub y/ indicate that capillary rise does not occur readily in these dies. The same was found to be true of hot-pressed and reaction-sintered Si3N4 obtained commercially. However, when dies were formed by depositing CVD layers on shaped silicon slabs, a column of molten silicon (approx. 2.5 cm high) was maintained in each CVD die while being heated (approx. 30 min) in contact with a crucible of molten silicon. Preliminary wetting of dies appears necessary for EFG growth. Several ribbon growth experiments were performed in our new ribbon growth facility from V-shaped dies. Both CVD Si3N4 and CVD SiO3 /sub y/ coatings were used on the die parts. There is also a problem with the wetting of SiO3 /sub y/ in the inverted ribbon growth process but not with Si3N4 layers. After about 90 min in contact with the melt, however, silicon flows into the defining slot in the case of SiO3 /sub y/ coatings.
