Category Archives: Black Silicon Carbides

Silicon Carbide Grit – news and technical data on this abrasive sandblasting media

Abrasive Grade Silicon Carbide – Uses Of

Silicon Carbide Grit

Silicon Carbide Grit & Powder

The main uses for abrasive grade Silicon Carbides (Carborundum) are:

  • anti-slip abrasives
  • sandblasting abrasives
  • bonded abrasives
  • coated abrasives
  • polishing/lapping compounds
  • tumbling media (including lapidary or rock tumbling uses)
  • wire-sawing abrasives
  • sintering
  • filling up ceramic parts

Today, there are many high tech uses for varying grades of Silicon Carbide such as electronics, brake pads, ceramics, LED’s, diodes, transistors, semiconductive research, heating elements, even jewelry.  Gone are the days when Silicon Carbide was known only as an abrasive.

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Silicon Carbide – Interesting Historical Facts

Black Silicon Carbide Abrasive

Silicon Carbide Sandblasting Abrasive

Silicon Carbide (SiC) was the first synthetic abrasive to be produced and also the first to be commercialized.  1891 was the year that silicon carbide production began, and thus revolutionized the abrasive industry as a whole.  Before 1891, almost all abrasives were naturally found such as rocks and minerals.

By 1900 SiC production was at 1,200 metric tons, carrying an estimated value of $263,000.  Mainly used in the lapidary industries, it was a replacement for diamond powder.  At that time, the only other manufactrued abrasive was crushed steel and as a contrast in volume, crushed steel production was only 320 tons, carrying a rather paultry value of ~$50,000.

With exception only given to diamond and garnet, by the year 2000, manufactured abrasives dominated the high end abrasive industries.  Unlike natural abrasives, manufactured abrasives could be tightly controlled, thus ensuring uniform properties like hardness and grit size.  A further benefit was the ability to customize the manufacturing process to meet exact specified needs, based on the end application.  While being more expensive that natural abrasives, their durablity and efficiency made them more cost effective overall.  They are therefore used heavily in the metal finishing, cutting, and polishing fields.

In short, manufactured abrasives are extensively used today in finishing numerous products.

 

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Number One Cause Of Premature Coatings Failure

The most common cause of premature coatings failure is improper ANCHOR PATTERN.

What is anchor pattern?  It is a term used to describe the roughness (etch, or profile) that is created on a surface when sandblasted.  The Anchor Pattern is measured in 1/1000th of an inch, which is called a MIL.  Paint coatings are also measured in MILS as well, making it a term that is easy to remember.

Coatings require specific mils of anchor pattern in order to properly adhere to the surface it is applied to.  Each coating will have different requirements.  Therefore, you cannot simply sandblast a surface clean and then apply paint to it without technical information on what mils profile that particular coating requires (among other factors).  If you simply guess at what profile you need, you risk premature coatings failure.

If you have no access at all to the coating manufacture’s technical data and need to make an educated guess, you will want to consider the following rule of thumb:

The mils of anchor pattern you create on the surface to be coated, should be 25 to 30% of the DRY film thickness of the total coatings system BUT NEVER greater than the dry film thickness of the primer coat unless additional coats are to be applied immediately.

Also key to understand is that the wet mils of a coating will be different than the dry mils of a coating.  Many coatings shrink tremendously, depending on the percentage of solids contained within them.  Make sure that the anchor pattern you create when sandblasting is much shallower than the total coatings when dry.

Other factors that impact the development of anchor pattern include the type of steel you are blasting (including hardness and chemical composition), how the steel was formed, prior use of the steel, the type of abrasive you use to create the anchor pattern (including size, shape, hardness, and velocity), as well as what type of blast nozzle you choose to use and how you use it (such as angle and distance to the work surface).

The chart below is a crude approximation of abrasive size to anchor pattern, and should thus be used only as a starting point only for both centrifugal wheel and pressure blasting.

  • 1 Mil Profile = G80 Steel Grit, 100 Mesh Garnet, S110 Steel Shot, 3060 Coal Slag
  • 1.5 Mil Profile = G50 Steel Grit, 100 Mesh Garnet, S170 Steel Shot, 3060 Coal Slag
  • 2.0 Mil Profile = G40 Steel Grit, 3060 possibly also 80 Mesh Garnet, 36 Grit Aluminum Oxide, 3060 Coal Slag, 3060 Copper Slag
  • 2.5 Mil Profile = G40 Steel Grit, 3060 Mesh Garnet, 24 Grit Aluminum Oxide, 2040 Coal Slag, 2050 Copper Slag
  • 3 – 4 Mil Profiles = G25 Steel Grit, 36 possibly also 3060 Mesh Garnet, 16 Grit Aluminum Oxide, 2050 or 1230 Copper Slag, 1240 Coal Slag

 

 

 

 

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