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A metal alumina ball and race

Posted by weiye on Thursday, March 24, 2011 3:44:23 AM
A microscopic look at the surface finish of a metal alumina ball and race, shows peaks and valleys on both surfaces. Lubricants fill in these valleys with incompressible fluids like oil and grease. This prevents metal-to-metal contact between ball and race.

But if the peaks do touch, the contact area is so small that even a small force on the ball or race results in pressures exceeding 1,000,000 psi. This causes cold welding between the ball and the race.

Bearings that use ceramics like silicon nitride, alumina, or zirconia overcome this problem by eliminating cold welding; Ceramic balls can’t weld to twin screw extruder. Ceramic materials also resist acids, alkalis, and salt. For both these reasons, bearings using ceramic balls and races don’t need oil or grease.


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The general issue with the alumina ball

Posted by weiye on Tuesday, March 08, 2011 9:47:24 PM
The general issue with the alumina ball was that they generated intense heat and most of the steel ball bearings either spun off a lot of particles which destroyed the lubricant or interfere with the normal functioning of the ball bearings. To overcome this problem ceramic as a material was suggested which generally was used in the space shuttles when they entered the earth's atmosphere.

That said the ball bearings were invented which were like two rolling surfaces which had the inner and the outer sleeve separated by small steel balls. These steel balls transfer the weight from the outer sleeve to inner sleeve. The balls play a very important role whe it comes to ball bearings.

Ceramic ball bearings are now being used at every conceivable place instead of the regular ball bearings. Ceramic is being the material used in most of the place where intense heat is generated. Friction is general caused by two surfaces being rubbed against each other which causes resistance and generates heat. Scientists discovered the wheel and applied that theory of a single point of PVC pipe which caused the less surface area to be in contact and that means less resistance.

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Such an alumina ball by product is not preferred

Posted by weiye on Thursday, January 06, 2011 1:26:30 AM
However, the thermal spraying method has a drawback that unit heat energy requirement is large, resulting in high costs. In addition, the thus produced alumina, although predominantly containing alumina, includes by products, such as alumina. Such an alumina ball by product is not preferred since the product exhibits low thermal conductivity.

The present invention relates to particulate alumina ball and to an industrial, economical method for producing particulate alumina which is particularly useful for materials, such as substrate material and sealing material for electronic parts, fillers, finish lapping material and aggregates incorporated into refractory, glass, ceramic, or composites thereof; has a narrow particle size distribution profile; causes little wear; and exhibits excellent flow characteristics.

The invention also relates to particulate alumina produced through the method and to a composition containing the particulate alumina. There has also been known a thermal spraying method in which total station produced through the Bayer method is jetted into high-temperature plasma or oxygen-hydrogen flame to thereby produce roundish crystal particles through melting and rapid quenching.
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how to separate the alumina ball

Posted by weiye on Wednesday, December 22, 2010 12:23:12 AM
In an alternative method, finely divided high-alumina refractory and water are admixed, but without the iron, and formed in an extruder to provide cylinders of suitable size. These cylinders are tumbled in a rotary drum so as to provide a firstsized wet alumina ball.

The Tosco process of retorting oil shales employs a cocurrent flow of hot alumina ball and oil shale in a rotating drum means. The oil shale takes up heat from the balls, and the oil vapors produced are drawn off into a collection system, leaving a spent shale admixed with the balls. The spent shale is transferred to a furnace where residue-carbon is burned off to provide reheating of the balls.

The main advantages of the Tosco system are the relatively high throughput rates achieved inproportion to the size of equipment, and the production of high-BTU off-gas since there is no dilution thereof by combustion products. However, one serious disadvantage of the total station has been just how to separate the alumina ball from the spentshale.
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alumina ball makes these particles suitable for use as fluid bed catalyst carriers

Posted by weiye on Wednesday, December 08, 2010 2:28:39 AM

The unique combination of alumina ball makes these particles suitable for use as fluid bed catalyst carriers, especially for fluid bed reactors operated at temperatures of above about 800 C. in the presence of steam. This invention further relates to processes for producing particles having this combination of properties.

The alumina ball particles are especially suited for use as fluid bed catalyst carriers for use in environments involving the presence of steam, particularly at high temperatures.

This invention relates to friable particles having the following combination of properties: a sieve shaker content of at least about 98.5%, a surface area of less than about 1 m 2 /g, an attrition resistance as shown by a weight loss of less than about 0.30 weight % per hour, a particle size of about 30 to 110 microns, a tap density of less than about 1.9 g/cc, a generally spherical shape, and sufficient porosity to hold catalytic metals.
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Stained glass art

Posted by weiye on Wednesday, September 16, 2009 3:05:58 AM
 

Everyone loves stained glass windows or stained glass panels especially on a sunny day. It is truly a beautiful art form. The earliest evidence of the practice of stained glass was probably during the 5th or 6th century in Europe, during the time of Charlemagne. These beautiful creations would adorn the windows of the early churches all throughout Europe and many can even still be seen today.
   The height of the stained glass art form in Europe was probably during the Middle Ages, and it was happening all over Europe. From Paris to Rome, to cities in England, incredible works of massive stained glass windows adorn 100’s of Catholic churches and cathedrals with the artwork of the many different stories of the bible. Designs became more daring, intricate and grandiose. The art form has evolved today from the two dimensional flat panels and windows to include stained glass sculptures and 3 dimensional structures.
     In making a stained glass panel, one first starts with the design or stained glass pattern. The design of the art work will dictate the structure of the window or panel. Once the different colored glass is decided upon and cut to its specific location on the panel, it will be held there by lead. The outline of shapes within the panel where the glass will be fitted to are called “cames” and have been traditionally made of lead. The finished piece should be able to hold up structurally. If the finished work is to be a window, planning in its design should take into account the different stresses the window will suffer once it is installed. During the 19th century, artists started using the copper foil method which consisted of wrapping the edges of the glass pieces in copper foil and then soldering them together. This allowed artists like Louis Comfort Tiffany to make intricate 3 dimensional stained glass works such as lamps and light fixtures.
     Stained glass panels and art work are still very popular today, especially the Tiffany styled works. You can find beautiful tiffany lamps shapes to decorate your home. You may even want to add a nice stained glass panel that you can hang over your kitchen window to let the beautiful morning light in. If you want to be even more daring and you can afford it, you can have a custom-made window into a stained glass work of art.
  If you are looking for a great selection of stained glass lamps, tiffany floor lamp, tiffany table lamps, tiffany ceiling lamps, you’ve come to the right place. Simply browse through our categories to find information and products ranging from the Tiffany stained glass lamps to custom stained glass panels.
    Stained glass making as a hobby has also gained in popularity as of late. Simply look for our stained glass starter’s kit, and you can be on your way to make your own stained glass designs. You can find a good learning resource here also. Simply go to our Learn Stained Glass section.
    We hope you enjoy perusing through our site, and we hope you get as inspired about stained glass art as we are!

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