What Is The Difference Between Graphitization And Carbonization?

Graphitization is an industrial process in which carbon is converted into graphite. This is a microstructural change that occurs in carbon or low-alloy steel, which is exposed to temperatures of 425 to 550 degrees Celsius for a long time, such as one thousand hours. This is a kind of embrittlement. For example, the microstructure of carbon molybdenum steel typically contains pearlite (a mixture of ferrite and cementite). When this material undergoes graphitization treatment, it will cause pearlite to decompose into ferrite and randomly dispersed graphite. This can lead to embrittlement of the steel, and when these graphite particles are randomly distributed throughout the matrix, it can result in a moderate decrease in strength. However, we can prevent graphitization by using materials with higher resistance that are less sensitive to graphitization. In addition, we can modify the environment (for example, by increasing pH or reducing chloride content). There is another method to prevent graphitization, which includes using coatings for cathodic protection of cast iron.

Carbonization is an industrial process in which organic matter is converted into carbon. The organic matter we are considering here includes plant and animal carcasses. This process occurs through destructive distillation. This is a pyrolysis reaction, considered a complex process in which we can observe many chemical reactions occurring simultaneously. For example, dehydrogenation, condensation, hydrogen transfer, and isomerization. The carbonization process is different from the carbonization process because carbonization is a faster process because its reaction rate is many orders of magnitude faster. Usually, the applied heat can control the degree of carbonization and the residual content of foreign elements. For example, at a temperature of 1200K, the carbon content of the residue is about 90% by weight, while at a temperature of about 1600K, the carbon content of the residue is about 99% by weight. Usually, carbonization is an exothermic reaction that we can make self-sustaining or use as an energy source that does not form any traces of carbon dioxide gas. However, if biological materials are exposed to sudden changes in heat (such as in a nuclear explosion), the biological material will quickly carbonize and become solid carbon.

Graphitization and carbonization are two industrial processes that involve carbon as a reactant or product. But carbonization involves converting organic matter into carbon, while graphitization involves converting carbon into graphite. Therefore, carbonization is a chemical change, while graphitization is a microstructural change.