Summary
Phospho degreasing in industry, basic principles
Introduction
Phospho degreasing is the industrial process capable of chemically converting a ferrous surface, making it, at the same time, cleansed, through the degreasing action, and phosphated.
In the processing chain of pieces of ferrous material, the surface conversion treatment is carried out to modify the chemical-physical properties on the surface of the product. This operation has the aim of extending the life of the piece and preparing it for subsequent painting treatments. The presence of surfactants in the formulations increases the degreasing power by removing impurities and greasiness due to previous processes which could compromise the painting itself, leaving uncovered areas in which humidity and air can chemically attack the product and damage it.
The surface conversion reaction
The phospho degreasing process is essential not only to facilitate painting, but also to form a chemical barrier on the surface of the piece, creating anchoring points for the paint so that it is more stable and long-lasting.
The barrier acts as a shield for the product, preventing air and humidity from penetrating and damaging the piece, thus avoiding surface oxidation reactions and the formation of rust.
Amorphous phosphating
Amorphous phosphating refers to the process through which a thin layer largely made up of amorphous Iron II phosphate is deposited on a steel surface, the thickness of which can vary from 0.1 to 0.6 µm, i.e. to say approximately from 0.2 to 1.2 g/m2, in the case of metals other than ferrous ones there will be an acid wash and the salts that will form will be equally useful for the painting phase.
The salt spray test
In order to evaluate the corrosion resistance of metallic materials it is possible to carry out the salt spray test regulated according to UNI EN ISO 9227:2023. This test has the advantage of detecting discontinuities, such as pores and other defects in some metallic, organic, anodic oxide and conversion coatings. It is therefore possible to quantify the effectiveness of the painting on the piece and consequently the effectiveness of the phospho degreasing treatment: main barrier to corrosion and source of anchoring to paint.
The neutral chamber test involves introducing the painted product into an environment with a controlled atmosphere of a corrosive nature and the hours necessary for the environment to affect the sample are measured.
Phosphoric acid, chemistry and applications
Chemical nature
Phosphoric acid is an inorganic chemical compound that belongs to the family of mineral acids. Its full name would be orthophosphoric acid, where the prefix distinguishes it from other acids that can be formed with the element phosphorus.Its chemical formula is H₃PO₄.
The chemical compound is a triacid, meaning it can release up to three protons, in aqueous solution. It is a strong acid and is used in various industrial and commercial applications, it can be found in the form of a crystalline solid or, more commonly, in an aqueous solution. Phosphoric acid reacts with bases to form salts called phosphates.
The applications
Some examples of uses include: the food industry, the chemical industry, the metallurgical industry and electronics: phosphoric acid is used in the food industry as a food additive to regulate the acidity of food products, it is often used in meat products, carbonated drinks and packaged foods. It is also used in the chemical sector as a reagent in various syntheses and industrial processes, such as the production of drugs or phosphate fertilizers used in agriculture, given that phosphorus is an essential nutrient for plant growth.
It is used to treat drinking and waste water, contributing to the control of pH and the elimination of impurities. In fact, phosphoric acid, due to its corrosive nature, is used in degreasing products, such as, for example, detergents, depollutants, degreasers, descalers and phosphodegreasers.
Phosphoric acid in phospho degreasing
Phosphoric acid plays a crucial role in the phospho degreasing process: it binds to the metal and deposits salts on the surface forming a film, this is a modification of the chemical structure. However, the salts that form and deposit can be removed; the subsequent painting phase must be carried out promptly otherwise there could be a partial detachment of the barrier, thus losing anchoring points for the paint and creating critical areas in which the atmospheric humidity could in the future attack and damage the piece.
FIPROKIM phospho degreasing products
The FIPROPHOS line
FIPROKIM SRL offers a wide line of phospho-degreasing products capable of guaranteeing the cleaning and simultaneous deposition of amorphous or crystalline phosphate coatings on multi-metal surfaces or components, these ensure a homogeneous substrate capable of protecting the artefacts and surfaces from corrosion , allowing excellent adhesion to paints or subsequent conversion processes. FIPROPHOS stands out for the great variety of formulations, for optimal treatments both for specific single metals such as iron, cast iron or aluminium, and for treating multimetal products; and by processing technique: immersion, lance or spray. Each product is researched to guarantee the best performance in the most different process conditions to satisfy every customer need by adding specific additives or accelerators.
The FIPROKIM laboratory
The FIPROKIM SRL technicians are available to monitor the start-up and operation of the system, also producing customer-specific operation manuals. The laboratory also carries out periodic checks in order to maintain the efficiency of the bathroom at the highest level. . Inside the laboratory there is also the equipment necessary to conduct the UNI EN ISO 9227:2023 test, i.e. the salt spray test, to quantify the hours of corrosion resistance. This equipment plays a key role in internally testing new products under development and in monitoring our customers' processes by verifying the effectiveness of the process and the correct corrosion resistance of the products treated with our FIPROPHOS products.
These are the main products of the line:
FIPROPHOS 510
Light-layer multimetal phosphodegreaser, with antiscalants. Applicable by spray and heat.
FIPROPHOS 517
Light-layer multimetal phosphodegreaser, with anti-corrosion and foaming additives. For use with pressure washer lances.
FIPROPHOS 530
Phosphodegreaser for iron and cast iron, high layer, with added corrosion inhibitors for line stoppages. To be used by hot spray.
FIPROPHOS 540
Light layer multimetal phosphorogreaser, with nitric, chlorates and molybdates. Applicable by spray, hot.
FIPROPHOS 545
Light-layer multimetal phosphorogreaser, to be used by spray at medium-low temperatures.
CHEMICAL PRODUCTS