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- US3389458A - Crystallized glass ceramic coatings - Google Patents
- International Journal of Heat and Mass Transfer (v.104, #C)
- Structure and Properties of Ceramics
- Heat resistant pyroceram domestic ware
- Glass-Ceramics Their Production
- Use of waste materials in the construction industry
- The Florida cattleman and livestock journal
- WO2008027300A2 - Glass articles and process for making the same - Google Patents
US3389458A - Crystallized glass ceramic coatings - Google PatentsVIDEO ON THE TOPIC: Incineration residues found in a Czech forest
Rawlings, J. Wu, A. ABSTRACT Glass-ceramics are polycrystalline materials of fine microstructure that are produced by the controlled crystallisation devitrification of a glass. Numerous silicate based wastes, such as coal combustion ash, slag from steel production, fly ash and filter dusts from waste incinerators, mud from metal hydrometallurgy, different types of sludge as well as glass cullet or mixtures of them have been considered for the production of glass-ceramics.
Developments of glass-. Properties and. The review reveals that considerable knowledge and expertise has been accumulated on the process of transformation of silicate waste into useful glass-ceramic products. These glass-ceramics are attractive as building materials for usage as construction and architectural components or for other specialised technical applications requiring a combination of suitable thermo-mechanical properties.
Previous attempts to commercialise glass-ceramics from waste and to scale-up production for industrial exploitation are also discussed. It is important to emphasise a number of points in this statement on glassceramics. Firstly, only specific glass compositions are suitable precursors for glass-ceramics; some glasses are too stable and difficult to crystallise, such as ordinary window glass, whereas others crystallise too readily in an uncontrollable manner resulting in undesirable microstructures.
Secondly, the heat treatment is critical to the attainment of an acceptable and reproducible product. As will be discussed later, a range of generic heat treatments procedures are used each of which has to be carefully developed and modified for a specific glass composition . One or more crystalline phases may form during heat treatment and as their composition is normally different from the precursor parent glass, it follows that the composition of the residual glass is also different to the parent glass.
The mechanical properties of glass-ceramics are superior to those of the parent glass. In addition, glass-ceramics may exhibit other distinct properties which are beneficial for particular applications, as exemplified by the extremely small coefficient of thermal expansion of certain compositions in the Li2O-Al2O3-SiO2 system which consequently are suitable for thermal shock resistant applications .
A wide range of glass-ceramics with tailored properties have been developed and several comprehensive review articles and dedicated books on their production, properties and applications, have been published .
There has been considerable research on the production of glass-ceramics from silicate waste in the last few decades. However, to the authors knowledge, there is no previous review article on this topic. This review is intended to cover this gap in literature; it will consider the production.
In the nucleation stage small, stable volumes of the product crystalline phase are formed, usually at preferred sites in the parent glass. The preferred sites are interfaces within the parent glass or the free surface. The latter is usually undesirable as the resulting glass-ceramic microstructure often consists of large oriented crystals that are detrimental to mechanical properties. However, in a few instances an oriented structure is beneficial, e. In most cases internal nucleation, also known as bulk nucleation, is required and the parent glass composition is chosen to contain species that enhance this form of nucleation.
These species are termed nucleating agents and may be metallic e. The rate of nucleation is very temperature dependent as illustrated in Figure 1 a. Once a stable nucleus has been formed the crystal growth stage commences. The driving force for this process is the difference in volume or chemical free energy, Gv, between the glass and crystalline states.
Models, involving the terms Gv and Ga, have been developed for the temperature dependence of the growth rate and the form of the resulting curve is given in Figure 1 a. Further in-depth treatment of the glass crystallisation process can be found in the previous cited works [1, 3]. The first stage is a low temperature heat treatment at a temperature that gives a high nucleation rate around TN in Figure 1a thus forming a high density of nuclei throughout the interior of the glass.
A high density of nuclei is important as it leads to a desirable microstructure consisting of a large number of small crystals. The second stage is a higher temperature heat treatment at around temperature TG to produce growth of the nuclei at a reasonable rate.
The parent glass may be shaped prior to crystallisation employing any of the well-established, traditional glass shaping methods such as casting and forming  or more special methods such as extrusion . Glass production and the subsequent heat treatments are in general energy intensive and therefore expensive.
If there is extensive overlap of the rate curves then nucleation and growth can take place during a single-stage heat treatment at temperature TNG as indicated in Figure 2. The rate curves, particularly the nucleation rate curve, is sensitive to composition and hence by optimising the glass composition it is, in some cases, possible to obtain the necessary overlap.
By judicious choice of nucleating agents, this was first achieved for the glass-ceramic system known as Silceram , as will be discussed later.
This led to the development of the production of certain glass-ceramics by a controlled, usually very slow, cooling of the parent glass from the molten state without a hold at an intermediate temperature.
With this method, referred to in the recent literature as the petrurgic method [14, 15], both nucleation and crystal growth can take place during the cooling. Both the modified conventional single-stage and the petrurgic methods are more economical that the conventional method two-stage. As there are limitations on the size and shape of components that may be cold compacted, and also a cost in producing a powder, this method is only used if an obvious benefit is identified.
In most cases there is little advantage in compacting and sintering a glass-ceramic powder because a high sintering temperature is required and the properties of the final product do not differ significantly from those of glass-ceramics produced by the other routes. It is more attractive to sinter a parent glass powder, which sinters by a viscous flow mechanism at lower temperatures .
It is important to consider the rates of viscous flow sintering and crystallisation and the interaction of these processes. If crystallisation is too rapid the resulting high degree of crystallinity will hinder the low temperature sintering leading to an unacceptable amount of porosity [22, 23]. On the other hand, if sintering is fully completed before crystallisation, then the final product is unlikely to differ significantly from those fabricated by other methods.
With appropriate rates it is possible in some cases to fabricate a dense glass-ceramics by a sintering process in which both densification and crystallisation take. The technological significance of this process as well as the theoretical complexities of its kinetics have been discussed in the literature . Optimisation of composition and sintering temperature can lead to different microstructures, and even different crystalline phases, compared to those from the conventional method, and hence different properties of the product.
Pressure assisted densification methods such as hot pressing and HIPping have also been successfully applied for production of glass-ceramics from powders.
Although these methods give improved products exhibiting near full densification, they are more expensive than cold pressing and sintering and thus unlikely to be employed for processing wastes into monolithic glass-ceramics.
Powder technology facilitates the production of dispersion reinforced glass-ceramic matrix composites . Fabrication of these particle-reinforced composites involves intimately mixing the powdered parent glass with the reinforcement in the required proportions. The mixture is then shaped, sintered and crystallised. Hard and rigid inclusions used as reinforcement hinder the sintering process. The production of continuous fibre reinforced glass-ceramics is more complex and requires dedicated apparatus .
For both particulate- and fibre-reinforced glass-ceramics the densification is usually carried out by hot pressing and a final heat treatment is required to achieve crystallisation of the glass matrix.
Thus all the methods for glass-ceramic production discussed previously may be used with glass produced by this route. However, the sol-gel method will not be discussed further in this review as it is not applicable for the production of glass-ceramics from waste materials. It follows that for efficient use of the worlds resources recycling and reuse of waste is necessary. Recycling is the selection, classification and reemployment of waste as a raw material to produce the same, or very similar product, to the parent material, e.
Reuse is the processing of waste to produce a useful product that is not similar to the material whose manufacture produced the waste. The present review is concerned with reuse of waste materials to produce glass-ceramics. The versatility of the glass-ceramic production process is manifested by the many wastes that have been used as raw materials for glass-ceramics, which include coal fly ash , mud from zinc hydrometallurgy , slag from steel production [13, ], ash and slag from waste incinerators , red mud from alumina production , waste glass from lamp and other glass products  as well as electric-arc furnace dust and foundry sands .
Much work has been carried out on the immobilisation of nuclear waste in glass and ceramic matrices and recently there has been some interest in the use of glass-ceramic matrices for this purpose [61, 62]. However, although a waste material is involved it is not the major component of the glass-ceramic and neither is the product for recycling or reuse but just for storage of the radioactive waste.
This area of glass-ceramics will therefore not be covered in this review. To produce an appropriate parent glass for crystallisation, additions to the wastes are often required.
It must be pointed out, however, that there is always a trade-off between the amount of waste recycled and the optimisation of properties of the new products. In general, since the main objective is to reutilise the waste material, the quantity of pure materials or non-waste additions introduced for improving performance must be kept as low as possible. Due to the wide variety of industrial wastes used in the production of glass-ceramics, we have subdivided according to the types of waste employed in the review for easy reference and clarity.
Blast-furnace slag was the first silicate waste to be thoroughly investigated as a source material for glass-ceramics. The first attempt to commercialise a glass-ceramic from slag was by the British Iron and Steel Research Association in the late s .
This glass-ceramic was known as Slagceram and it was produced by the conventional, two-stage, heat treatment method [64, 65]. A similar material, Slagsitall, was developed in the former Soviet Union at about the same time [66, 67].
More recent works have investigated the effect of adding nucleating agents to the slag; in particular glass-ceramics with acceptable properties were produced using a two-stage heat treatment and addition of titania .
It is interesting to review in more detail the effect of TiO2 as nucleating agent in glass-ceramics from slags. As in many studies thermal analysis was used to assist in the selection of heat treatment schedule. For samples with no additional TiO2, the shallow exothermic peaks indicated that surface crystallisation was the predominant mechanism of glass-ceramic formation . This led to grain refinement of the crystallites. A nucleation temperature of C was employed and crystallisation temperatures in the range CC investigated.
The optimised crystallisation temperature was found to be C, and the main crystalline phase of the slag-based glass-ceramic with TiO2 as an additive was a melilite solid solution, containing gehlenite and akermanite Ca2MgSi2O7.
The subsequent mechanical testing results showed the effect of the crystallisation temperature and TiO2 content. It was also observed that as the amount of nucleating agent increases, the wear rate of the glass-ceramic material appeared to be decreasing.
Another example of TiO2 nucleated slag-based glass-ceramics comes from the study of Gomes et al. A combination of steelwork slag, limestone, sand, bauxite, and ilmenite was used to produce glass-ceramics via the conventional melting followed by heat treatments. The authors did not disclose the exact quantity of each component used in the raw mixture, but the slag was claimed to be the majority component. Sand was used to increase the SiO2 content, CaO and Al2O3 contents were enriched by the inclusion of limestone and bauxite, respectively and ilmenite was used to introduce TiO2 as the nucleating agent.
Through microstructural and thermal analysis, the authors selected C and C for the nucleation temperature and the crystallisation stage respectively and claimed that this heat treatment resulted in bulk crystallisation. The main crystalline phases were diopside CaMgSi2O6 and augite.
Samples of this composition were nucleated at C followed by an isothermal crystallisation heat treatment at C. It was found that augite was the main crystalline phase after 5 minutes but a second crystalline phase wollastonite, CaSiO3 was observed after 50 minutes at C. Fredericci et al. The internal crystallisation was only possible through the presence of Pt3Fe, a compound formed during the melting stage of the slag through reaction with the platinum crucible.
However, either Pt3Fe is a poor nucleating agent or there was an insufficient amount present as differential scanning calorimetry DSC curves for glass powders of different particle sizes showed the crystallisation peaks to shift to higher temperatures with increasing particle size; this suggests that bulk crystallisation was not significant and that surface crystallisation was dominant . As far as other glass-ceramic systems are concerned, El-Alaily  recently investigated some basic physical and chemical properties of lithium silicate glass and glass-ceramics derived from blast furnace slag with additions.
Thus El-Alaily  was able to melt slag-containing mixtures at C, which is C or more.
Nid yw statws neu berchnogaeth hawlfraint yr adnodd hwn yn hysbys delweddau ar gyfer gyda diolch i'r Llyfrgell Brydeinig. We have not ueeu liau so gallant ns tt.? Now, byafuUnotieewehopeto atone. The on. Mcrethev come, nbout! Jty in number.
International Journal of Heat and Mass Transfer (v.104, #C)
This banner text can have markup. Search the history of over billion web pages on the Internet. Full text of " Concrete stone manufacture " See other formats Google This is a digital copy of a book that was preserved for generations on Hbrary shelves before it was carefully scanned by Google as part of a project to make the world's books discoverable online. It has survived long enough for the copyright to expire and the book to enter the public domain.
Structure and Properties of Ceramics
Costs for the construction of the "box" are distributed approximately in the proportions indicated in the table. However, these percentages of costs for each particular house will differ significantly in some indicators. This can be seen in the example of the construction of an individual two-story brick residential building of TEKS Service. The cost is indicated in specific units. The facade of the house is shown in Fig. Living area The building area isSEE VIDEO BY TOPIC: Pin your basket!
The main finishing materials in modern construction include finishing mortars and concretes ; natural and artificial masonry materials ; decorative ceramics ; materials and items made from wood, paper, glass, plastic, and metals; and paints and varnishes. Finishing materials are usually designed for interior or exterior finishing ; some materials are used for both for example, natural decorative stone, ceramic materials, and architectural glass. A special group consists of materials and items for covering floors , which must meet a number of specific requirements negligible wear , high impact strength, and so on. Finishing materials also include acoustic materials , which are used simultaneously as sound-absorbing coatings and as a decorative finish for the interiors of theaters, concert halls, and motion-picture theaters. An arbitrary distinction is made between finishing materials proper, which are used mainly to form decorative and protective coatings varnishes and paints, wallpaper, polymeric films, linoleum, and so on , and structural finishing materials , which also perform the functions of enclosing members and are components of such members decorative concrete , facing brick , glass blocks , and molded glass. A large group of finishing materials consists of facing materials , which are produced in the form of sheets, slabs, and tiles for example, asbestos-cement sheets, Stemalit, ceramic mosaic slabs and tiles, and decorative laminated-paper plastic and which are generally distinguished by their good service and architectural qualities. Under modern industrial construction conditions it is expedient to produce the facing during the manufacture of prefabricated units and to deliver the units to the assembly point with finished surfaces for example, ceramic mosaic tiles are laid in a form and concreted together with the wall panels or staircase landings. The most important finishing materials are discussed below. A traditional finishing material is natural stone , which is durable and has an attractive appearance.
Heat resistant pyroceram domestic ware
Ian W. The safe storage in glass-based materials of both radioactive and non-radioactive hazardous wastes is covered in a single book, making it unique Provides a comprehensive and timely reference source at this critical time in waste management, including an extensive and up-to-date bibliography in all areas outlined to waste conversion and related technologies, both radioactive and non-radioactive Brings together all aspects of waste vitrification, draws comparisons between the different types of wastes and treatments, and outlines where lessons learnt in the radioactive waste field can be of benefit in the treatment of non-radioactive wastes. Ian Donald has specialised in various areas of glass technology for over 30 years. After receiving a PhD from the University of Leeds?
Jump to navigation. International Journal of Heat and Mass Transfer v. The effect of solar radiation on temperature distribution in outdoor human—clothing—environment systems by Yasuhiro Shimazaki; Shojiro Goto; Atsumasa Yoshida; Takanori Yamamoto The present study investigates heat transfer in the human—clothing—environment system under solar radiation. A new thermal model integrating the solar radiation absorption by clothing, as well as heat conduction within the air layer and heat convection on the clothing surface, is presented. The heat transfer in this system is simply explained based on the heat conduction equation; heat transfer relating to solar radiation is added as the source of heat generation at the surface of clothing. The temperature distributions inside clothing are well predicted with variations in the amount of solar radiation, ambient temperature, air gap depth, and radiative properties. Temperatures are increased or decreased linearly with changes in the air gap distance, confirming that the temperature of the air layer inside clothing is governed by conduction. Temperature distributions differ depending on solar radiation and also radiative properties, particularly absorptance, indicating that radiative heat transfer must be included to evaluate clothing heat transfer. In this study, melting of paraffin wax with Al 2 O 3 nanoparticles in a partially heated and cooled square cavity is investigated numerically. The thermally active parts of the enclosure which are facing each other are kept at different constant temperatures while the other parts of the enclosure are insulated.
Glass-Ceramics Their Production
The risk of the increased levels of radioactive radiations determines a special attitude to the atomic energy and radwastes RW and demands the acceptance of cardinal and operative measures on their isolation from people. As regards the glass matrixes, they allow to reduce the volume of the conditioned waste products and to improve sharply physical and chemical properties of the matrix, but at the same time due to an amorphous structure have a number of disadvantages such as: high fragility, presence of numerous structural defects, low homogeneity and density and also rather low radiation resistance. During the last stage the optimal regimes of the extraction of radioactive nuclides by zeolites have been specified on the pilot machine. Thus, in the static and dynamic conditions the significant reduction of LRW volumes up to times with their transformation into a hard phase has been achieved. At the same time, the reduction of LRW volumes was considered by the participants of the above mentioned project as a temporary measure till the development of the technology of sitallization of sorbents with high concentration of radioactive nuclides and slurries got from the Deep Evaporation Machine. This direction of works, on which the prediscovery had been carried out, demands much more time and new financial support. In the suggested project the high-competent personnel will participate. Particularly the participants of the project made the following steps:. Armenia natural and technogenic materials volcanic glass, perlite, tuff, slag, litoid pumice, boron-containing travertine, barite and etc.
Use of waste materials in the construction industry
United States Patent 0 Our invention relates in inorganic coatings and en- 7 capsulants and particularly to such coatings comprised of crystallized glass ceramics. It has been disclosed in applications Ser. Obviously the glass must fuse at temperatures below the melting point of the conductors which are usually copper or silver. At room temperatures common glasses provide excellent electrical resistance but at temperatures close to their fusion points the electrical resistivity of glass dropssharply and so does thev resistance to cut through or the tendency of the wires to push through the softened glass and short circuit to adjacent turns. It would, therefore, be desirable to use very high melting glass compositions for the insulation and encapsulation of electrical apparatus, and preferably the glass should have a fusion point at least degrees above the operating temperature of the coil. If the coil is operated at temperatures close to the melting point of the conductors there has not been, prior to the present invention, any means of fusing the desired high melting point insulation or encapsulant glass insulation on the conductors. The use of crystallizable glass does not solve the problem, for the finely divided glass will, of course, crystallize before it fuses, because the necessary nuclei are formed in the glass when it cools prior to being formed into a frit or fiber.
The Florida cattleman and livestock journal
See pages 12 andi 10S of this Report. RAPO 1O,.
WO2008027300A2 - Glass articles and process for making the same - Google Patents
From Wikipedia, the free encyclopedia Jump to navigation Jump to search This is a list of building materials. Many types of building materials are used in the construction industry to create buildings and structures. These categories of materials and products are used by architects and construction project managers to specify the materials and methods used for building projects.
Rawlings, J. Wu, A. ABSTRACT Glass-ceramics are polycrystalline materials of fine microstructure that are produced by the controlled crystallisation devitrification of a glass.
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