1. Background of Corrosion in Equipment Manufacturing

Corrosion of mechanical equipment refers to the change in shape or size due to chemical or electrochemical reactions between the equipment and the surrounding media, leading to the damage of the equipment. It is one of the most common phenomena in mechanical industry production. The corrosion of machinery makes production impossible, as it significantly shortens the equipment's service life. In severe cases, it can even cause equipment explosions, leading to energy waste, environmental pollution, and human casualties.

As is well known, mechanical equipment is outdoor machinery that is exposed to harsh environments such as atmospheric conditions (including marine, industrial, urban, and rural atmospheres) and varying water qualities (seawater, river water). It constantly endures varying degrees of corrosion from different regions and environments, which leads to various chronic and recurrent diseases of engineering machinery.

I. Reference Standards

Current national standards, relevant regulations, and mandatory standard provisions;

"Code for Construction and Acceptance of Building Anti-corrosion Engineering" (GB50212-2002)

"Standard for Corrosion and Rust Removal Levels of Steel Surface Before Coating" (GB8923-1988)

"Safety Regulations for Coating Operations and Safety Management Rules" (GB6514-1995)

"Quality Requirements for Anti-corrosion Coatings" (GB6514-1991)

"Safety Regulations for Coating Operations, Paint Process Safety, and Ventilation Purification" (DJ/T6931-1999)

"Code for Construction and Acceptance of Industrial Equipment and Pipeline Anti-corrosion Engineering" (HGJ229-91)

"Safety Regulations for Coating Operations and Safety of Surface Preparation Process" (GB7692-87)

"Noise Limits at Construction Sites" (GB12523-90)

ISO9001 Quality Management System Documents

ISO14001 Environmental Management System Documents

GB/T28001 Occupational Health and Safety Management System Documents

I. Design Basis

Environmental Conditions: The corrosion level of atmospheric environments on steel structures can be determined according to Table 1.

I. Corrosion Analysis of Construction Machinery

As is well known, construction machinery is outdoor equipment that is exposed to harsh environments such as outdoor atmosphere (including marine, industrial, urban, and rural atmospheres) and various water qualities (seawater, river water). It is subjected to various corrosive media from different regions and environments, causing a variety of “chronic diseases” and “common ailments” in construction machinery. First, most construction machinery operates in the field, with harsh working conditions and high intensity. Many machines have to work in humid, dusty, and even corrosive environments, and after a certain period of use, rusting often occurs to varying degrees. To extend the service life and ensure the machinery performs well, appropriate corrosion protection measures are usually implemented. The most widely used protection process is coating.

In the production and manufacturing process, the coating of various mechanical components helps to prevent rust between processes, reducing losses and processing costs caused by rusting. More importantly, the surface coating plays a crucial role in preventing corrosion during the machine’s later service life. Furthermore, due to the rapid development of the domestic construction machinery manufacturing industry, many large machinery manufacturers export their products to countries in Africa, America, and even Europe. However, many construction machines exported by these companies are rejected upon arrival due to rusting during maritime transportation, as insufficient rust protection was applied. Therefore, corrosion protection of construction machinery during maritime transport has become a research hotspot.

There are two types of damage caused by metal corrosion: the first type is uniform corrosion. This occurs when the entire surface of the metal is corroded under the action of corrosive media. This type of corrosion is less harmful because the components have a certain cross-sectional size, and minor uniform corrosion does not significantly reduce the mechanical properties of the metal. However, in box-type metal structures, the internal surface may lose a layer of material, causing the web to become thinner, which should not be overlooked. The second type is localized corrosion. This occurs in localized areas of the metal body. This type of corrosion reduces the effective cross-sectional area of the component and makes it more susceptible to sudden failure (most notably bolts). Localized corrosion includes pitting corrosion and intergranular corrosion, which are much more harmful than uniform corrosion. Among these, intergranular corrosion is the most dangerous, as it propagates along the grain boundaries, damaging the connection between crystals, significantly reducing the mechanical properties of the metal. This detrimental effect is often difficult to detect.

Table 1: Corrosion Protection Plan for Construction Machinery Using Second-Generation Coatings

Table 2: Corrosion Protection Plan for Construction Machinery Using Fourth-Generation Graphene Coatings

I. Corrosion of Agricultural Machinery

Agricultural machinery is widely used in various working conditions, which are often harsh. The corrosion factors are complex, including atmospheric corrosion, moisture and heat corrosion from agricultural fields, as well as corrosion caused by fertilizers and pesticides, and the strong abrasive wear. Therefore, the corrosion of agricultural machinery is severe, and its lifespan in corrosive media environments is reduced compared to its original design. As the agricultural mechanization industry develops, the demand for materials will increase sharply, and the damage caused by corrosion will also become greater. Therefore, it is essential to study the corrosion laws of agricultural machinery, understand the factors controlling the corrosion rate, and adopt effective anti-corrosion measures according to local conditions to extend the service life of agricultural machinery, which is of significant importance to the national economy.

Most agricultural machinery operates in the field, and its working environment involves soil, water, and plants, enduring wind, sunlight, and rain throughout the year. Paddy field machinery also suffers from erosion by water and abrasion from soil. Therefore, the requirements for atmospheric corrosion resistance are more prominent than in other industries. Special attention should be paid to plant protection machinery, fertilizing machinery, mechanized pig and poultry farms, which not only bear certain dynamic loads but also come into contact with pesticides, fertilizers, and manure. During operation, they are subjected to both corrosive media and abrasion, leading to more severe corrosion. For example, manual pesticide machines in China have very short service lives, generally only a year, and some machines suffer severe corrosion within a year. Fertilizer machine components, typically low-carbon steel coated with anti-corrosion paint, have a lifespan of only about a year. Statistics show that the lifespan of steel wire rope scraper manure removal equipment is only one year, and the feed towers at Xiangfang Pig Farm are severely corroded within a year of use. In addition, there are problems such as cavitation corrosion in large axial flow pumps, microbial and water corrosion, and thermal corrosion in engines. Although agricultural machinery has implemented anti-corrosion measures with paint, corrosion still severely affects the service life of agricultural machinery due to various corrosive factors and abrasive impacts. Since the corrosion process is relatively slow, it has not received the necessary attention until now.

Agricultural machinery is often contaminated with dust and weeds during operation. Therefore, the cleaning of agricultural machinery should be taken seriously. The surface should be washed with clean water and then dried in the sun. If any rust or corrosion is found during cleaning, the surface should be cleaned quickly and coated with anti-corrosion paint.

When agricultural machinery is idle, it is best to park it indoors to prevent natural factors such as frost, rain, snow, and excessive sunlight from causing damage. Shelters should be built to ensure that the machinery is not exposed directly to sunlight or rain. During storage, the warehouse should be well-ventilated. Parts in direct contact with the ground should be supported by racks to prevent contact with the ground. It is inevitable that parts of agricultural machinery will peel off during production and use, so it must be repaired promptly before long-term storage to reduce continuous damage to worn parts. Plastic products installed on agricultural machinery should be protected from direct sunlight during idle periods to prevent deterioration and aging. If possible, they should be stored in a dry and ventilated place and coated with a protective surface layer.

Table 1: Anti-Corrosion Scheme for Agricultural Machinery Using Second-Generation Coatings

I. What is Mining Equipment

Mining equipment refers to machinery directly used for mineral extraction and beneficiation operations. This includes mining machinery and ore beneficiation machinery. The working principles and structures of prospecting machinery are largely similar or identical to those used in the extraction of similar minerals, and therefore, in a broad sense, prospecting machinery can be classified as mining machinery. Additionally, mining operations also use a large number of cranes, conveyors, ventilators, and drainage machinery. This term broadly refers to equipment used in various mining production processes such as excavation, screening, transportation, and specialized crushing equipment, mining equipment, drilling equipment, excavation equipment, coal mining equipment, oil drilling and extraction equipment, ore beneficiation drying equipment, etc.

Mining machinery operates under harsh conditions and is subject to severe wear. Parts that perform relative motion suffer from friction, which leads to continuous wear. Since mining machinery is mostly heavy-duty machinery, the wear issue is particularly prominent. When the wear exceeds a certain limit, the reasonable fit between parts is destroyed, leading to a decline or deterioration in the mechanical performance, and thus causing various mechanical failures. Therefore, analyzing the types and forms of wear in mining machinery, identifying the patterns of wear, and finding ways to reduce wear are essential.

Due to the high humidity in mining environments, with moisture content reaching up to 80%, machinery made of metal materials is severely corroded. Additionally, the pH level in mining environments is high, exceeding 6.5, causing chemical reactions in the equipment. Furthermore, the machinery generates large amounts of electrical current during operation, which accelerates the corrosion, ultimately leading to wear failure of the mining machinery.

Table 1: New Anti-Corrosion Solution Using Graphene Coatings

Table 2: Maintenance Anti-Corrosion Solution Using Fourth-Generation Graphene Coatings

I. What is a Machine Tool?

A machine tool: is a machine used to manufacture other machines, also known as the "mother machine." It is generally classified into metal-cutting machine tools, forging machine tools, woodworking machine tools, and so on. A machine tool is a machine used to process metal blanks into machine parts, and since it is the machine that manufactures machines, it is also called the "mother machine" or "tool machine," commonly referred to as a machine tool. In modern mechanical manufacturing, there are many methods for processing mechanical parts: in addition to cutting, there are also casting, forging, welding, stamping, extrusion, etc. However, any parts that require higher precision and finer surface roughness generally need to be finally processed on a machine tool by cutting. In general machine manufacturing, the workload on the machine tool accounts for about 40%-60% of the total manufacturing workload of the machine.

When painting mechanical products like machine tools, a certain level of precision is required. Since high temperatures can cause thermal deformation in components, affecting machining accuracy, these machines, especially those with high precision requirements, generally use materials that are either air-drying or thermally curing anticorrosive coatings. Commonly used air-drying anticorrosive coatings include chlorinated polyethylene paint and acrylic-modified paints. Commonly used thermally curing paints include polyurethane and epoxy coatings. Due to the imbalance in the production cycle of machine tools and other mechanical products, the drying time for the coating needs to be quick. According to relevant regulations, the drying time for the primer and topcoat should not exceed 0.5 hours for surface drying and 2 hours for through-drying, with putty drying not exceeding 4 hours.

II. Table 1: Anticorrosive Solution Using Graphene Coatings