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How to choose a quality charcoal carburizer for carburizing parts

How to choose “correct” carb?

Charcoal Carburetor represents charcoal grains , which are saturated with carbon and covered with a film of barium carbonate.
According to GOST 2407-83 charcoal carburetor must meet the following criteria:

Name indicator	Normal
Barium carbon dioxide mass fraction, %	20±2
Mass fraction of calcium carbonate, %, max	2,0
Mass fraction of total sulfur, %, max	0.04
Mass fraction of silicon dioxide, %, max	0.2
Mass fraction of volatile substances, %, max	7,0
Mass fraction of water, %, max	4,0
Size: mass fraction of the remainder, % -on a sieve with canvas No. 100, no more -on a sieve with canvas No. 36, no less than -per pallet, max	6,0 93 2

Where to use carburetor?

Charcoal Carb < span style="font-family: georgia, palatino, serif; font-size: 12pt;">used in the chemical-thermal treatment of steel, in the process of carburizing parts (carbon saturation). And it has a direct impact on the quality indicators of this operations. Namely:

to the depth of carbon saturation
its optimal saturation is up to 0.9-1% in the surface layer of the metal
hardness of cemented layer
abrasion resistance and many other carburizing results.

Barium carbonate as part of the carburetor ensures the formation of a gaseous environment during carburizing and is an accelerator of the whole process. And Calcium carbonate helps to eliminate the sintering of particles during heat treatment.

IMPORTANT! The main factor that determines the quality of a solid carburizer is the raw material from which it is made.

The carburetor must be made from charcoal GOST 7657-84 grade A of the highest grade. The mass fraction of non-volatile carbon in such coal is at least 90%. The granulometric composition is made up of grains of no more than 5% less than 12mm and no more than 5% of grains less than 25mm.

These sizes of coal provide good circulation of gases during grouting. In addition, in order to obtain such a fraction of coal, it is necessary to take commercial coal, the size of which is more than 25 mm, and crush it mechanically. Naturally, when crushing, a waste of about 30% is formed, which of course increases the cost of a high-quality carburetor.

Please note that it is at this stage that unscrupulous manufacturers reduce the price of your product. They produce a carburetor from charcoal screenings, which is essentially a waste product.

This screening represents charred twigs, pieces of bark, etc.. This is a violation of GOST 2407-83 normative documentation standards. And, of course, such charcoal will contain less than 50% carbon. But, on the other hand, impurities of ash and volatile substances that will create an unfavorable environment during cementation will be in excess.

How much does a GOST carburetor cost?

To calculate the price of a hard carb,

What is the danger of using a low-quality charcoal carburizer when grouting?

Firstly, it violates the main goals of heat treatment. As a result, we will not get the required hard hardened metal surface.
Secondly, the composition of the carburetor directly affects the rate and order of carbonation of the steel. The use of the “wrong” carburizer can lead to hardening cracks and flaking of the carburized layer as a result of carbon saturation of the surface layer of the metal too quickly. The depth of carbon penetration also depends on the activity of the carburetor.

A low-quality carburetor is more angular in shape and has a whitish coating on the surface. Quality charcoal carburetor has rounded grains without whitish coating, mouse color.

Also, you can use a high-quality charcoal carburizer 2-3 times, and a low-quality one will burn out after one carburizing cycle. Because it simply does not have enough carbon, as in a product that is produced in accordance with GOST from grade A charcoal.

Quality carburetor can be reused with 15-30% fresh hard carb.

Given that carburizing with a solid carburizer takes quite a long time from 8 hours. And, also, it requires high energy costs to heat up to 900-950 degrees Celsius. That saving on the carburetor can lead to the release of defective products and much more significant costs. Accordingly, those enterprises that use a charcoal carburizer according to GOST 2407-83 from grade A charcoal for grouting will benefit. They will receive both high-quality durable cemented metal surfaces and additional economic benefits.