Analysis of the Current Situation and Development Trend of Marine Anti-corrosion Coatings Technology

Marine anti-corrosion is one of the key technologies in Marine engineering. Stress corrosion fracture (SCC), hydrogen embrittlement (HE), corrosion fatigue (CF), and intergranular corrosion (IC) caused by the corrosion of metals in the ocean can lead to sudden fractures in Marine steel structures, resulting in ecological disasters in the Marine environment and causing huge losses. In addition, the premature failure of anti-corrosion coatings on Marine engineering products and the downtime losses caused by coating maintenance are also considerable. Therefore, appropriate anti-corrosion technologies must be adopted to solve the problem.

In recent years, both at home and abroad, there has been increasing attention paid to Marine corrosion and protection. Although various materials resistant to seawater corrosion have been continuously introduced and various anti-corrosion construction technologies have also made great progress, they are still far from meeting the actual needs. There is a significant gap between China's research on anti-corrosion of Marine engineering structures and facilities and that of developed countries abroad. Some key technologies remain unsolved, and no technologies with independent intellectual property rights in China have been formed. Moreover, there is a lack of corresponding anti-corrosion norms and standards. All these have seriously affected the design, construction and safe operation of Marine engineering structures. Therefore, in response to the common and key anti-corrosion issues faced by key sea areas and major Marine projects in our country, conducting research on key technologies for long-term anti-corrosion of Marine engineering structures and facilities can not only prevent corrosion from occurring, avoid or reduce the maintenance and repair costs and economic losses caused by maintenance in later service, but also reduce the occurrence of major and serious accidents. Moreover, it can greatly enhance the safety of Marine engineering facilities, which is of great significance.

1. Requirements for Marine anti-corrosion coatings Marine anti-corrosion coatings refer to anti-corrosion coatings used in Marine environments. Due to the extremely harsh and highly corrosive Marine environment, Marine anti-corrosion is a subject that urgently needs to be seriously studied in the development of Marine engineering in China.

According to the material of the anti-corrosion object and the corrosion mechanism, Marine anti-corrosion coatings can be classified into Marine steel structure anti-corrosion coatings and non-steel structure anti-corrosion coatings. Marine steel structure anti-corrosion coatings mainly refer to the anti-corrosion coatings for large facilities such as transport ships, containers, offshore Bridges, port machinery, oil pipelines, and offshore oil platforms. Non-steel structure Marine anti-corrosion coatings mainly refer to the anti-corrosion coatings for Marine concrete structures. Marine anti-corrosion coatings mainly include inorganic zinc-rich, organic zinc-rich, silicone, epoxy, acrylic, polyurethane, fluorocarbon and polysiloxane coatings. Different coatings and coating systems can be selected according to the corrosion characteristics and anti-corrosion years of different Marine environments.

Marine anti-corrosion coatings are generally required to have the following properties: ① Good physical properties. It has good impermeability to corrosive media and good adhesion to the surface of steel. ② It has good mechanical properties. Resistant to seawater erosion, sea ice collision and wear caused by ship docking; ③ It has excellent chemical properties. Resistant to erosion by seawater, salt spray, oil, chemicals, ultraviolet rays, etc. ④ It has good compatibility with electrochemical protection systems. The coatings in the splash zone and the full immersion zone should have cathodic disbondment resistance. ⑤ It has good construction performance. High-quality coating construction can be carried out on different structures under various environmental conditions. ⑥ It meets the requirements of health, environmental protection and safety. The solid content of the coating is required to be high, and the content of volatile organic compounds (VOC) should meet the requirements of national or international standards. ⑦ Other special requirements. For example: The coating of the freshwater tank is required to be non-toxic and meet the requirements of national hygiene certification. The chlorine content that can be filtered out in the coating used on the surface of stainless steel shall not exceed 200mg/kg, and the coating shall not contain zinc. The coating of the ship's ballast tank shall comply with the requirements of the "Performance Standard for Protective Coatings of Ship Ballast Tanks" of the International Maritime Bureau (IMO). Coatings on parts of ships below the waterline are required to prevent the adhesion of Marine organisms, etc.

The commonly used international standards for Marine heavy-duty anti-corrosion coatings mainly include: ①ISO12944 protective coating system for corrosion protection of steel structures; ②NORSOKM501 surface treatment and protective coating; ③ Performance requirements for ISO20340 offshore and related structural protective coating systems; ④ Corrosion control of offshore structures by NACESPO108 protective coating; ⑤IMO Marine Ballast Tank Protective Coating Performance Standard (PSPC).

Marine anti-corrosion coatings and their coating combinations usually need to meet the requirements of relevant anti-corrosion standards such as ISO12944, NORSOKM501, NACESPO108 and ISO20340. Generally, strict corrosion tests and certifications must be passed in advance. The main test items include: ① Salt spray (salt water) resistance test for 4000 hours; ② Cathodic disbondment resistance test; ③ Wet heat resistance test for 4000 hours; ④ Cyclic corrosion test for 420 hours [1-4].

2. Key points of research and development for Marine anti-corrosion coatings

The research and development of Marine anti-corrosion coatings is characterized by high technological content, long development cycle, large investment, high technical difficulty and high risk. Abroad, the research and development of Marine anti-corrosion coatings mainly focuses on large companies with strong strength or departments supported by the government. For instance, several major companies such as IP in the UK, PPG in the US, Hemple in Denmark, Jotun in Norway and Kansai Paint in Japan all have over a hundred years of history in the development of related coatings. They have formed a very strict and rigorous system in aspects such as coating production and supply, quality supervision, coating standards and on-site coating management. At present, the products of these companies have occupied the main market of Marine anti-corrosion coatings in our country [5].

The production of Marine anti-corrosion coatings in China is mainly concentrated in a few coating enterprises in Qingdao, Shanghai, Dalian, Tianjin, Changzhou, Guangzhou and Xiamen. Research work is mainly carried out in research institutions such as the Institute of Oceanology, Chinese Academy of Sciences, Institute of Metal Corrosion, Chinese Academy of Sciences, Marine Chemical Research Institute, CNOOC Changzhou Coatings Research Institute and CSSC 725 Research Institute. In recent years, although quality management and supervision institutions such as the "Xiamen Testing Station for Marine Coatings of China Shipbuilding Industry" and the "Quality Supervision Center for Marine Coatings Products" have been established, the overall technical level still lags behind that of advanced countries.

At present, the research and development of Marine heavy-duty anti-corrosion coatings abroad mainly focuses on the following aspects.

2.1 Long Service Life

Due to the increasing number of super-large steel structures and the characteristics of the sea areas they are located in, which do not have the conditions for direct recoating or returning to the shore for construction, it is required to develop Marine anti-corrosion coatings with an extremely long service life. The most ideal situation is that the service life of the coating, including the extended service life after on-site direct painting and maintenance, is equivalent to the service life of the steel structure equipment, that is, the coating and the equipment are designed to have the same service life. Only minor maintenance is required during use and no repainting is necessary. The coating galvanizing in Belgium belongs to the organic high-zinc-rich coating, with the metallic zinc content in the dry film reaching 96%. In the coastal Marine atmosphere environment of Oslo, Norway, the average annual coating loss of a single zinc-coated film with a thickness of 120μm applied to a steel bridge after 15 years was measured to be only 1μm [6].

The most typical successful case of inorganic zinc-rich coating application is the 250km oil pipeline project in Morganwyalla, Australia. The anti-corrosion treatment adopted a single-layer water-based inorganic zinc-rich coating, which has remained in good condition for over 50 years without any corrosion. The refinery built by EXXON of the United States on Sulfur Island uses a single-layer zinc silicate anti-corrosion coating. After 15 years, only a small part of the coating needs to be repaired, and after the repair, it remains intact and rust-free for 4 years.

As topcoats, the weather resistance of fluorocarbon coatings and polysiloxane coatings currently developed can reach over 15 years. Such as the trifluorovinyl chloride FEVE fluorocarbon paint produced by Asahi Glass, a subsidiary of Japan, the tetrafluoroethylene FEVE fluorocarbon paint produced by Daikin, the acrylic polysiloxane coating interfine979 produced by International Paint Company, and the epoxy polysiloxane coating PSX700 produced by Ameron Corporation of the United States, etc.

2.2 Low surface treatment

As the cost of pretreatment before coating accounts for 60% of the total coating cost, low surface treatment coatings have become one of the important research directions for anti-corrosion coatings.

Over the years, China's flooring industry has achieved remarkable development, making outstanding contributions in economic growth, improving people's livelihoods, increasing employment, expanding exports and social welfare. However, in recent years, some unfavorable factors such as inflation, labor costs and real estate regulation have put huge pressure on the survival of some small and medium-sized flooring enterprises. How can we further demonstrate the floor's unparalleled vitality and competitiveness?

The spring of the development of flooring enterprises has come to an end

A senior figure who has been in the flooring business for over a decade pointed out that the spring of development for flooring enterprises has come to an end. Chinese flooring enterprises are now facing "four major bottlenecks" : the appreciation of the RMB, the increase in the prices of bulk raw materials, the accelerated rise in labor costs, and the intensification of conflicts between management and employees, which leads to a continuous increase in management costs. The emergence of development bottlenecks indicates that the development crisis of flooring enterprises has arrived.

In fact, the development crisis of flooring enterprises is not a new occurrence. The global financial crisis in 2008 should have been a watershed for flooring enterprises, as they could have taken advantage of the power of the financial crisis to complete industrial upgrading and transformation of profit models. However, with the intervention of national forces and the stimulation of 4 trillion yuan in funds, the macroeconomy recovered rapidly, and the development crisis of flooring enterprises was once again concealed.

The corporate predicaments such as the appreciation of the RMB and inflation that emerged in 2011 can be regarded as a continuation of the financial crisis, but not a recurrence of the crisis. Instead, they are the adverse consequences of the previous development crisis being repeatedly concealed and ignored. Therefore, it is high time for flooring enterprises to seriously consider their own development strategies.

Talents and mechanisms are core assets

In the face of huge survival pressure, flooring enterprises must make the choice of transformation and upgrading, and this transformation and upgrading is precisely the process of reshaping the values of entrepreneurs.

Industry insiders believe that the Chinese entrepreneurial spirit advocates "Heaven rewards the diligent" and a down-to-earth and pragmatic spirit. However, in the operation of flooring enterprises, more and more enterprises feel increasingly exhausted. There are many reasons for this, such as: The emergence of economic cycles, the development and changes of industries, the backwardness of products and services, the intensification of market competition, the deterioration of internal contradictions, the lack of team incentives, the increasing scale, and the growing assets, etc. However, when it comes back to the essence, what flooring enterprises lack is innovation and respect and protection for talents.

Floor entrepreneurs excel in equipment investment but are weak in establishing system architectures. Because equipment investment has the advantages of quick return on investment, simple operation, easy risk control and visible investment, coupled with the down-to-earth and pragmatic spirit, the business model of many flooring enterprises follows a low-cost expansion path. That is to say, the vast majority of them adopt a "productization" business model far from end customers. This model implies that the competitiveness of flooring enterprises is actually more about cost competitiveness rather than "customer competitiveness". The "belly" of enterprises is getting bigger and bigger, but the market has not expanded. It is inevitable that they will become more and more exhausted as they keep working.

It is precisely because the establishment of the system architecture is short that enterprises lack the necessary talent and mechanism soil for transformation. In response to this, the development mode of flooring enterprises should be changed, shifting from merely pursuing "quantitative" growth to pursuing "qualitative" growth. The soft power of the enterprise, such as the profit model, profitability, and core team, should be incorporated into the core assets of the enterprise. The differences between companies often lie in their soft power. Talent, customers, services, markets, systems and culture are the true values of a company that can thrive for a long time.

For flooring enterprises to transform, "Change starts with changing people."

For the transformation and upgrading of flooring enterprises, merely reshaping the entrepreneur's own values is far from enough. The transformation of flooring enterprises "starts with changing people". Human resources are the most important resources and the most crucial factor in an enterprise. The transformation and upgrading of flooring enterprises must first start with "people". If the "people" remain unchanged, there will be no sudden changes in output value, profit, technology, equipment, cash flow, new product research and development, market share or product quality. Once the "people" change, everything will change accordingly.

The quality of the operators in flooring enterprises fails to keep up with the development requirements of the market economy, which restricts the healthy and sustainable development of flooring enterprises. However, when it comes to the transformation and upgrading of their enterprises, the bosses of flooring companies often dare not or are unwilling to start with "changing people" first, which leads to repeated changes, stagnation, and a talent predicament of "unable to recruit, unable to utilize, unable to maintain, unable to retain, and unable to afford to damage".

Therefore, in the process of transformation and reform, a strategic height should be established, with the boss taking charge personally. Profit should come first, virtue should be emphasized, and an internal talent competition mechanism should be established. And only by giving employees the most valuable things at present can we motivate them to work like entrepreneurs. Only when an enterprise transitions from the "self-longevity" of an entrepreneur to the "longevity of the enterprise" can it truly undergo transformation and upgrading, and then radiate a brand-new youthful temperament.

The transformation and upgrading journey of flooring enterprises is fraught with hardship and pain. Both entrepreneurs and managers endure tremendous mental torment. The change also implies adjustments to the internal interest structure, including business, organization, salary, new preferences, and the impact of sudden transfers. However, once the "transformation and upgrading" battle is initiated, one can only bravely move forward, as there is no turning back. It is precisely because these difficulties and bottlenecks on the road of transformation and upgrading have been continuously resolved and broken through that enterprises have achieved continuous success and the group of respected entrepreneurs has been continuously expanding.

Looking at the current entire flooring market, compared with other wooden floors, bamboo floors, which use natural bamboo as the material, have relatively lower formaldehyde emissions. Their environmental friendliness is beyond doubt compared to wooden floors, and they have achieved a good connection with the current consumption trend of pursuing a low-carbon life in the market. However, bamboo flooring has always been at a disadvantage in the competition with wooden flooring and laminate flooring, mainly due to its own characteristic shortcomings. But with the new emergence and launch of the high-quality and environmentally friendly bamboo flooring market, the inherent shortcomings of bamboo flooring will also be made up. Industry insiders generally believe that this indicates that the turning point of consumption in China's bamboo flooring market is approaching.

Facing competition from domestic peers, a large number of bamboo flooring manufacturing enterprises that have shifted from exports to domestic sales are actually having a hard time. The emergence of new products and technologies in the bamboo flooring industry, high-margin brand operation and bamboo culture brands are the three major turning points for bamboo flooring to re-drive the domestic flooring market, and they are also the three new selling points.

The sales of bamboo flooring in China remain stagnant, accounting for only one-tenth of the wooden flooring market, and the sales volume is rather sluggish. Today, when consumers attach great importance to the concept of environmental protection, this situation must have its inherent factors. Facing the fierce competition in the domestic flooring industry, how Chinese bamboo flooring can seize the turning point in order to win the favor of consumers has become an urgent and crucial issue.

In the past, bamboo flooring was prone to cracking and deformation in heated rooms in the north due to its unstable performance, and its applicability was relatively poor. In the south, it was more likely to rot and be infested by insects compared to wooden flooring. Therefore, it has always occupied a very small share in the domestic market. However, with the emergence of the new technology of heavy bamboo flooring, the technology and performance of bamboo flooring products have all improved, and they can now compete with solid wood flooring on an equal footing.

High-density heavy bamboo mainly uses the renewable resource of Moso bamboo as raw material, replacing the traditional production method that uses wood as raw material. The utilization rate of moso bamboo is as high as over 90%, which is almost more than twice the raw material utilization rate of the traditional floor production method. Moreover, China has relatively abundant moso bamboo resources, which can not only achieve sustainable production and reduce costs, but also effectively protect the environment. It can develop rapidly without excessive consumption of natural resources.

Due to the fact that heavy bamboo flooring products are more stable and durable than before, their application scope and application areas are also wider. In terms of performance and application range, they have surpassed ordinary bamboo flooring, thus changing the competitive disadvantage of bamboo flooring. As a result, the performance of heavy bamboo flooring is now on par with that of solid wood flooring, and there is even a trend of surpassing the latter at one go.

The gross profit margin of the ordinary decoration and building materials industry is generally around 40%, and that of the wood flooring industry is over 30%. However, the general gross profit margin in the domestic bamboo flooring industry is only 20% or more