Before the steel anti-corrosion coating, spray cleaning rust removal how to choose the most suitable abrasive

Overview
the productivity and environmental stakes faced by sand blasting construction make it a clear requirement to be familiar with the properties of blasting abrasives to survive and maintain competitive advantage in today's business environment.surface
is an important step in establishing a protective coating system. Several trials over the years have concluded that coating construction on surfaces that provide a stable anchor-chain appearance in blast cleaning results in high-quality corrosion protection and durability
china
. In order to obtain proper surface roughness, abrasives suitable for engineering polishing requirements must be selected. In some cases, because blast residues can damage the cleanliness of the surface, less polished blast particles must be considered. Today's business environment is highly quality assurance and environmental requirements, so it is critical to be familiar with the properties of blasting abrasives. Unfortunately, no blast abrasive is suitable for all construction projects, and fortunately, there are many different types of abrasives and grades to ensure the completion of the project. Learning the characteristics of each abrasive can help you choose more efficient and costly blasting abrasives.determine the most appropriate blast abrasive for the project, the definition of abrasive must first be clear: abrasive refers to a substance used for grinding and polishing. It can be a by-product of a natural substance, a man-made plant, or a process. Frequently used materials include: 1
, silica sand;
2
, zircon;
3
, copper slag garnet;
4
, corn spike shaft grain;
5
, ceramic
;
6
, alumina
;
7
, nickel slag
;
8
, .
9
, walnut shell
;
10
,
olivine;
11
,
;
12
,
steel sand;
13
, plastic particles;
14
, steel pellets., the characteristics of abrasives
when selecting the required abrasives, the respective characteristics must be taken into account. These characteristics include abrasive hardness, shape, size, color, weight, chemical composition, availability, cost and environmental factors
,
preferably selected on a project-by-project basis.1
, hardness
abrasive hardness determines whether blast particles can form etching or an anchor-chain appearance on a particular substrate surface. One way to determine the hardness of an abrasive
is to
the Mohs hardness ruler. The ruler ranges from
1
to
10
, with
1
representing the softest (mica)
10
representing the hardest (diamond). The hardness of the sand blasting gran, which generally reaches the anchor chain-like appearance, is
6.0
or higher. However, there are also some requirements for the use of soft particles ranging from
3.0
to
4.5
that do not cause etching on the glass or steel surface, but remove foreign dirt
,
which provides surface cleanliness, primarily in areas where the substrate surface is not to be damaged or where blast particles or residues do not cause damage to the surrounding environment. Soft blasting grans is commonly used in areas surrounded by bearings or other fragile machines. Steel sand and steel pellets are hard abrasives and are
hardness
Rockwell C method. Hardness ranges from
42
to
65
. Steel sand forms etching on the surface of the steel structure, while steel balls form dents on the surface of the steel structure.2
, shapes
abrasives have different shapes,, blocky, semi-circular, or spular. Angled abrasives with sharp edges have the highest cleaning rate when removing tight material or dirt attached to the substrate. The sharp edge of the angled abrasive can make the steel surface form an anchor-chain appearance, which provides good mechanical attachment to the coating. Block abrasives guarantee good cleaning rates, except for dirt that is very difficult to remove. Semi-circular or spular abrasives can form dents in the surface, which are mainly used to increase surface hardness.3
, size
size of the abrasive affects the cleaning rate and the resulting anchor chain appearance. The U.S. screening method is a granular grading method that distinguishes between particle grade and packaging by the U.S. screening method or particle diameter-determined size method. Abrasives are usually divided into
4
to
325
, the smaller the size of the sieve, the larger the abrasive particles.
8-16 grade
grades are very rough and are mainly used on surfaces that are difficult

to clean or require a deep anchor chain
appearance
; Round or spherical blast particles are graded by particle diameters ranging in size from
0.070 to 0.660
feet.
use of a uniform grade size abrasives to ensure that the precise flow of the valve is measured by a blaster, a uniform grade of hard abrasives to ensure the surface stability of the substrate roughness.4
, color
if you are considering choosing an abrasive type, color is not very important, but in some cases is also a key factor. Surface residue after blasting affects appearance. Black abrasives are less reflective of sunlight than light dust, which is especially important when blasting in internal areas that require illumination. If the abrasives are not easily completely removed if they are constructed in an airtable area or in an area under repair, it is important to select the abrasive color from a aesthetic point of view.5
weight or gravity
weight of the abrasive affects surface cleanliness and surface roughness. Weight is expressed in
/
cubic feet, and the weight refers to the density of the particle, which means heavier than the weight. Under the same pressure, heavy ingests obtain a deeper anchor chain-like appearance. less dust than major abrasives
,
proportion of light particles on the substrate impact is small, mainly used for light blasting or polishing, removal of burrs and so on.6
chemical composition
in order to ensure compatibility with the substrate, the chemical composition of the abrasive must be considered. When blasting, blast particles are embedded in the substrate or leave residues, which can damage the protective coating system. If iron blasting is used on stainless steel substrates, embedded particles form corrosion electrodes on the substrate.
7
, availability
must ensure that the selected blast particles are sufficiently available, easy to obtain, and that the project is completed smoothly. For optimal engineering results, it is not recommended to replace the abrasives in the middle. Many abrasives are by-products of natural ore or other industries and are not easily supplied in large quantities in a timely manner.
8
, cost and
abrasive cost are the key factors in the project. In general, the choice of abrasives is determined by freight from the supplier to the construction site. The breakage rate of the abrasive is also important. The high recycling cost of abrasives can be reduced through full re-use in blast cabinets or blast rooms with recycling systems. The recirculation rate is determined by the blast pressure, hardness, stretch and size of the abrasive.9
, environmental impact and
are the final factors that determine abrasive selection. Includes: effects on the breathing of sand blasters. Workers must use breathing equipment during the blasting process and monitor the entire blasting process. When air flow is poor in blasting areas, proper dust recovery equipment must be used to reduce the amount of dust faced by workers. Additional safety and engineering controls should also be considered for toxic coatings in enclosed areas, taking into account abrasives dispersed into the soil.2. Categories and Characteristics of AbrasivesThe abrasive catalogues listed below are usually abrasives, not all of them, in order to provide more information to the reader and to arouse the reader's curiosity about finding the applicable abrasives around them. Familiarity with the performance characteristics of each abrasive provides a good start to the project's success. 1
, silica sand
is a cheap abrasive that is available in many parts of many countries. The mineral sand is sharp and the river sand is rounder.
Mohs
hardness is
6-7
, can form an etched or anchor chain-like appearance on the substrate surface
,
is available in a variety of sizes, brown or sepia
,
can be recycled and reusable, containing
95%-99%
silicon dioxide (
SiO2
). Due to the risk of silica lung disease, special control must be taken during blasting. The National Association for Occupational Safety and Health (
NIOSH
) recommends standard
PB-246-697
Part
6

a point
points
2
Description:
"
Uncontrolled silicon blasting will lead to a risk of silicon lung disease, which must be taken with special care. Silicon sand or other materials containing free silicon greater than
1%
must be prohibited as blasting abrasives during blasting.
"
further noted that the
most effective and direct way to eliminate the risk of silica lung disease is
to replace free silicon with a low-toxic material, and alternatives with free silicon content below
1%
should be considered in the sand blasting process.
" 2
cinders
cinders are by-products of the utility industry, blocky, free silicon content is less than
1%
.
Mohs
hardness of
6
, can form an etching or anchor chain-like appearance on the surface of the substrate, black with green gloss, there are various sizes, mainly composed of silicon oxide, alumina and iron oxide, can be recycled several times, but generally disposable, is a low-cost abrasive. 3
, copper slag
copper slag is a by-product of the copper mining industry, block, free silicon content is less than
1%
,
Mohs
hardness of
6
, can form an etched or anchor chain-like appearance on the surface of the substrate, due to the proportion of the assembly embedded substrate, black with gray gloss, with various sizes, is a cheap abrasive. 4
, nickel slag
nickel slag is a by-product, block, free silicon content is less than
1%
,
Mohs
hardness of
6
, can form an etching or anchor chain appearance on the surface of the substrate, there are various sizes, can be recycled many times, but generally disposable, is a low-cost abrasive. 5
, crossstone
crossstone is a natural ore, sharp angle, free silicon content of less than
1%
, composed of alumina and iron oxide,
Mohs
has a hardness of
7
, can form an etched or anchor chain-like appearance on the substrate surface, can be recycled multiple times, but for outdoor and blast cabinets and sand blasting rooms with recycling systems can only be used once, medium and small size. 6
, ceramic
ceramic is specially produced abrasive, sharp angle, free silicon content of less than
1%
, black-brown
/
gray,
Mohs
hardness of
7
, there are various sizes, can form etching or anchor chain appearance on the surface of the substrate, can be recycled multiple times. 7
, olivine
olivine is a natural ore, sharp angle, free silicon content of less than
1%
,
Mohs
has a hardness of
6.5
, can form an etched or anchor chain-like appearance on the surface of the substrate, pale green, with various sizes, the main components are silicon oxide, magnesium oxide, iron oxide, can be recycled many times, but for outdoor blasting and blasting cabinets and sand blasting rooms with recycling system can only be used once. 8
, zircon
zircon is a natural ore, sharp angle, free silicon content is less than
1%
, in
Moh
hardness At
6.5
, it can form an etched or anchor-chained appearance on the surface of the substrate, consisting of tannins, brown, and is used mainly in blasting cabinets and sand blasting rooms with recycling systems due to its fast cutting. 9
, alumina
ceramics are specially produced abrasives, sharp angle, free silicon content of less than
1%
, black,
Mohs
has a hardness of
8
, is available in a variety of sizes, can form an etched or anchor chain-like appearance on the substrate surface, can be recycled multiple times, because of its fast cutting, low dust, high cost, mainly used in blast cabinets and sand blasting rooms with recycling systems. <