วันอังคารที่ 22 มกราคม พ.ศ. 2556

High temperature insulation


High temperature insulation Calcium silicate
    Calcium silicate (often referred to by its shortened trade name Cal-Sil or Calsil) is the chemical compound Ca2SiO4, also known as calcium orthosilicate and sometimes formulated 2CaO.SiO2. It is one of group of compounds obtained by reacting calcium oxide and silica in various ratios[3] e.g. 3CaO•SiO2, Ca3SiO5; 2CaO•SiO2, Ca2SiO4; 3CaO•2SiO2, Ca3Si2O7 and CaO•SiO2, CaSiO3. Calcium orthosilicate is a white powder with a low bulk density and high physical water absorption. It is used as an anti-caking agent and an antacid. A white free-flowing powder derived from limestone and diatomaceous earth, calcium silicate has no known adverse effects to health[citation needed]. It is used in roads, insulation, bricks, roof tiles, table salt[4] and occurs in cements, where it is known as belite (or in cement chemist notation C2S).


High temperature insulation
   Calcium silicate is commonly used as a safe alternative to asbestos for high temperature insulation materials. Industrial grade piping and equipment insulation is often fabricated from calcium silicate. Its fabrication is a routine part of the curriculum for insulation apprentices. Calcium silicate competes in these realms against rockwool as well as proprietary insulation solids, such as perlite mixture and vermiculite bonded with sodium silicate. Although it is popularly considered an asbestos substitute, early uses of calcium silicate for insulation still made use of asbestos fibers.

Natural adhesives


Natural adhesives
      Natural adhesives are made from organic sources such as vegetable matter, starch (dextrin), natural resins or from animals e.g. casein or animal glue. They are often referred to as bioadhesives. One example is a simple paste made by cooking flour in water. Animal glues are traditionally used in bookbinding, wood joining, and many other areas but now are largely replaced by synthetic glues. Casein is mainly used to adhere glass bottle labels. Starch based adhesives are used in corrugated board production and paper sack production, paper tube winding, and wall paper adhesives. Masonite, a wood hardboard, was bonded using natural lignin, (although most modern MDF particle boards use synthetic thermosetting resins). Another form of natural adhesive is blood albumen (made from protein component of blood), which is used in the plywood industry. Animal glue remains the preferred glue of the luthier. Casein based glues are made by precipitating casein from milk protein using the acetic acid from vinegar. This forms curds, which are neutralized with a base, such as sodium bicarbonate (baking soda), to cause them to unclump and become a thicker plastic-like substance

Synthetic adhesives


Synthetic adhesives
     Synthetic adhesives are based on elastomers, thermoplastics, emulsions, and thermosets. Examples of thermosetting adhesives are: epoxy, polyurethane, cyanoacrylate and acrylic polymers. See also post-it notes. The first commercially produced synthetic adhesive was Karlsons klister in the 1920s.

วันศุกร์ที่ 12 ตุลาคม พ.ศ. 2555

Aluminium


Aluminium ( /ˌæljuːˈmɪniəm/ al-ew-min-ee-əm) or aluminum (American English;  /əˈluːmɪnəm/ ə-loo-mi-nəm) is a chemical element in the boron group with symbol Al and atomic number 13. It is silvery white, and it is not soluble in water under normal circumstances.
Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth's crust. It makes up about 8% by weight of the Earth's solid surface. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals.[6] The chief ore of aluminium is bauxite.
Aluminium is remarkable for the metal's low density and for its ability to resist corrosion due to the phenomenon of passivation. Structural components made from aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials. The most useful compounds of aluminium, at least on a weight basis, are the oxides and sulfates.
Despite its prevalence in the environment, aluminium salts are not known to be used by any form of life. In keeping with its pervasiveness, aluminium is well tolerated by plants and animals.[7] Owing to their prevalence, potential beneficial (or otherwise) biological roles of aluminium

วันพุธที่ 18 กรกฎาคม พ.ศ. 2555

Masonry heater


          A masonry heater (or masonary stove, ceramic stove, tile stove) is a device for warming an interior space by capturing the heat from periodic burning of fuel (usually wood), and then radiating the heat at a fairly constant temperature for a long period . The technology has existed in different forms: from the Roman hypocaust to the Austrian/German kachelofen. The hypocaust is a system for heating the floors and walls of buildings (especiallybaths) using the smoke and exhaust of a single fire. In Eastern and Northern Europe and North Asia, these kachelofens (or steinofens) evolved in many different forms and names: for example the Russian Stove/Fireplace (Russian: Русская печь), the Finnish Stove (in Finnish: pystyuuni or kaakeliuuni, "tile oven") and the Swedish Stove (in Swedish: kakelugn, "tile stove" or "contra-flow stove") associated with Carl Johan Cronstedt. The Chinese developed the same principle into their Kang bed-stove. The masonry heater has gained renewed domestic popularity recently because of its heating efficiency.


Thank for Info : http://en.wikipedia.org

Porcelain tile


          Porcelain tiles are ceramic tiles with a water absorption rate of less than 0.5 percent that are used to cover floors and walls. They can either be unglazed or glazed.
          The hardness of the tile is rated from zero to five according to the ASTM C1027 (or ISO 10545-7) test for surface abrasion resistance of glazed tile. This rating, (sometimes mistakenly called the PEI rating) determines the tiles suitability for various end use conditions.
          Large-scale production of porcelain tile is undertaken in many countries, with the major producers being China, Italy, Spain and Turkey. There are also countries undertaking small-scale production, such as Australia and strong growth in developing countries such as Brazil.
         Porcelain Tile is also a very common trend in tile installation. There are many different styles of porcelain tiles on the market and they have proved to outperform ceramic tile in durability and looks.
          It is important to note that the differences of the body of the porcelain tile, as it relates to ceramic tile, has caused many "job failures" of tile installations. Tile setters that are self trained and novices to the industry will often use cements or mastic to install the impervious body of the porcelain tile to a substrate only to have delamination occur rather quickly. Highly Modified cements are necessary for installation of this material due to the very qualities that make it such a durable long lasting decorative surface. Those specifications are determined by and dictated as industry standards by the Tile Council of America, and supported by the Tile Contractors Association.

Thank for Info : http://en.wikipedia.org

วันพฤหัสบดีที่ 12 กรกฎาคม พ.ศ. 2555

Silicon nitride


          Silicon nitride is a chemical compound of silicon and nitrogen. If powdered silicon is heated between 1300 °C and 1400 °C in an atmosphere of nitrogen, trisilicon tetranitride, Si3N4 is formed. The silicon sample weight increases progressively due to the chemical combination of silicon and nitrogen. Without an iron catalyst, the reaction is complete after several hours (~7), when no further weight increase due to nitrogen absorption (per gram of silicon) is detected. In addition to Si3N4, several other silicon nitride phases (with chemical formulas corresponding to varying degrees of nitridation/Si oxidation state) have been reported in the literature, for example, the gaseous disilicon mononitride (Si2N); silicon mononitride (SiN), and silicon sesquinitride (Si2N3), each of which are stoichiometric phases. As with other refractories, the products obtained in these high-temperature syntheses depends on the reaction conditions (e.g. time, temperature, and starting materials including the reactants and container materials), as well as the mode of purification. However, the existence of the sesquinitride has since come into question.
The Si3N4 phase is the most chemically inert (being decomposed by dilute HF and hot H2SO4). It is also the most thermodynamically stable of the silicon nitrides. Hence, Si3N4 is the most commercially important of the silicon nitrides and is generally understood as what is being referred to where the term "silicon nitride" is used.
          Silicon nitride (i.e. Si3N4) is a hard ceramic having high strength over a broad temperature range, moderate thermal conductivity, low coefficient of thermal expansion, moderately high elastic modulus, and unusually high fracture toughness for a ceramic. This combination of properties leads to excellent thermal shock resistance, ability to withstand high structural loads to high temperature, and superior wear resistance. Silicon nitride is mostly used in high-endurance and high-temperature applications, such as gas turbines, car engine parts, bearings and metal working and cutting tools. Silicon nitride bearings are used in the main engines of the NASA's Space shuttles. Thin silicon nitride films are a popular insulating layer in silicon-based electronics and silicon nitride cantilevers are the sensing parts of atomic force microscopes.

Thank for Info : http://en.wikipedia.org