SIBUR Modernized Glycol Production SIBUR Modernized Glycol Production
The SIBUR holding company completed a modernization of its production processes at its facilities in the Central region, reducing ethylene consumption in the...
Chemical Materials in Agriculture Chemical Materials in Agriculture:
Science does not stand still, and in agriculture new fertilizers are constantly being invented — formulations to improve the quality of grown produce,...
Overview Article: Ammonium Bifluoride We have prepared an overview article on the chemical properties of Ammonium bifluoride.
The article gives a general description of ammonium bifluoride from the standpoint of chemical reactivity. It...
How to Increase the Fire Resistance of Materials?
Flame retardants are used to improve the fire resistance of materials.
Flame retardants are substances added to materials of organic origin to increase their fire-resistant properties. They slow down the combustion and ignition of the material.
The action of flame retardants is based on:
1. melting...
Classification of dangerous goods by hazard level (ADR hazard class) in Russia is based on GOST 19433-88 "Dangerous goods. Classification and labeling," introduced in 1990.
Classes of Dangerous Goods:
Class
Subclass
Name
1
explosive materials
1.1
explosives with a mass explosion hazard
1.2
explosives with no mass explosion...
Mineral Fertilizers
Everyone knows that various fertilizers, both mineral and organic, are introduced into soil to increase its fertility.
Today the market offers a huge variety of products for mineral soil enrichment. Science continually studies and invents new and new combinations of mineral components, such as potassium, phosphorus, ammonia,...
Chemical corrosion of metals, in general terms, proceeds as diffusion of metal particles (ions or atoms) through a film formed by the corrosion products. This film grows larger over time. From the air (or another medium, for example, water), oxygen ions or atoms diffuse in the opposite direction.
At the first stage, adsorption of the oxidizer itself occurs on the metal. The process can be described by the formula:
Me + O2 = Me/2O — this means a surface covered with adsorbed O2. This is an ionic bond — the metal gives up two electrons to oxygen.
In some metals, corrosion proceeds with self-inhibition; for example, aluminum forms aluminum oxide on the surface, and further chemical corrosion of the metal does not occur.
Corrosion Protection
Alloying — a special additive is added to the base metal. For example, stainless steels.
Protective films — coating the surface with a low-permeability substance. For example, varnish or paint, which prevent contact between the metal and the oxidizer. This does not protect against corrosion, but only greatly slows down absorption and further processes.
Priming — often applied before painting. Primer also does not protect against corrosion but serves as an additional barrier against the penetration of the oxidizer. Red lead (orange lead) is considered the most effective primer.
Phosphating — solutions are applied to the surface: phosphoric acid and other orthophosphates (for example, of zinc, iron, or manganese).
Electrochemical protection — in industry, a metal product is placed in a zinc phosphate solution and an alternating current is applied. This is usually done for better adhesion of the surface to the paint applied later.
Silicate coating — coating with porcelain or glass-like materials (for example, enamels). Such materials are impermeable to oxidizers even at high operating temperatures, but they are very susceptible to thermal fluctuations and mechanical shocks.
Cement coatings — everyone remembers the pipes that children like to climb on. Such pipes are coated with cement, but it flakes off under mechanical impact.
Metal coatings — naturally coated with another metal (different from the one being protected). These coating metals must themselves have low susceptibility to corrosion.
Corrosion inhibitors — this is one of the most effective methods. More details in a separate article on corrosion inhibitors. The following materials are most often used:
