Hou Baorong, academician of the Chinese Academy of Engineering: Corrosion protection technology and the realization of the "double carbon" goal

Source: High-tech and industrialization

With the development of modern society, steel production has made it possible for infrastructure construction and industrial development. As the most used metal material by human beings, the loss caused by corrosion of steel cannot be underestimated. In 1970, the British survey report proposed that the loss caused by steel corrosion could reach 1.365 billion pounds per year, accounting for 3.5% of the BRITISH GDP; according to the survey, the loss caused by corrosion in China in 2014 was 210 billion, equivalent to 3.34% of the GDP of that year, and each citizen had to bear 1555 yuan. Underneath these huge amounts, there is a huge amount of carbon emissions.

Hou Baorong

At the moment when China's "double carbon" goal is proposed, how to reduce the huge carbon emissions caused by losses by improving the corrosion protection ability of steel has become a problem that scientists must face. Recently, at the 2021 World Marine Science and Technology Conference held in Qingdao, Shandong Province, Hou Baorong, academician of the Chinese Academy of Engineering, chairman of the Marine Anti-corrosion Industry Technology Innovation Strategic Alliance, chairman of the Global Corrosion Survey China, and researcher of the Institute of Oceanology of the Chinese Academy of Sciences, introduced the latest anti-corrosion technology.

Emphasis is placed on anti-corrosion technology to help achieve double carbon

In 1967, the steel bar of the Silver Bridge in Ohio, USA, was broken due to long-term corrosion, resulting in the death of 46 people. In 1983, the pier at Yamashita Pier in Yokohama, Japan, although it had adopted a protective method to increase the corrosion margin, collapsed due to concentrated corrosion. "The corrosion of building materials is a very dangerous thing that lurks around each of us." Hou Baorong pointed out.

In order to prevent irreparable damage due to corrosion, the government often takes regular repair measures. In 1960, several illegals broke into the American Statue of Liberty and hung banners in protest. After the incident, the government inspected the interior of the Statue of Liberty and found that there were many holes caused by corrosion in the Statue of Liberty, 1/3 of the 1.2-ton steel skeleton rivets were loose, damaged or detached, and nearly half of the brackets were rusted, and there was a danger of falling apart at any time. In May 1981, the United States established the Statue of Liberty Restoration Committee, raising $350 million. Repair the copper skin and replace all the parts, including 1825 special ribbed beams, which took 36 hours to manufacture, and it took the workers six months to complete the work. "It's not hard to see that the money spent to repair the losses caused by corrosion is huge, and the carbon emissions behind this are also huge."

The harm of carbon dioxide can not be underestimated, its source is mainly emitted into the air by the combustion of oil, coal, natural gas, in addition, oil, coal in the production process will also release carbon dioxide, other including organic matter fecal fermentation will also produce carbon dioxide.

What is the impact of carbon dioxide on humans? When the carbon dioxide in the air is less than 1%, there is no obvious harm to the human body; if the carbon dioxide exceeds 1%, it will be dizzy and depressed; when the carbon dioxide reaches 5%, people will have headaches; and when it reaches 10%, people will be delirious.

There are also many tragedies caused by excessive carbon dioxide concentrations, such as the carbon dioxide lake in Qimen County, Anhui Province, which caused 5 people to suffocate and die. The carbon dioxide density is greater than the air density, which is easy to accumulate in the mountains, forming a carbon dioxide lake, while forcing the air layer to move up, resulting in a decrease in the oxygen content at the bottom.

Because of the insulation of carbon dioxide, when the concentration of carbon dioxide increases, the temperature of the Earth's surface will gradually increase. According to forecasts, by the middle of the 21st century, the global temperature will rise by 1.5 °C ~ 4.5 °C, and the resulting sea level rise will also have a huge impact on the living environment of human beings and endanger human safety.

So how do we deal with the increase in carbon dioxide? On 12 December 2015, nearly 200 parties to the United Nations Framework Convention on Climate Change unanimously adopted the Paris Agreement at the Paris Climate Change Conference to make arrangements for global action on climate change beyond 2020. The parties decided at the time to invite UN Secretary-General Ban Ki-moon to serve as depositary of the Agreement, and so far more than 190 countries have signed the Paris Agreement.

China submitted a nationally determined contribution document ahead of the Paris Conference, proposing that China's carbon dioxide emissions will peak around 2030 and proposing a "double carbon" target. "Carbon peaking" refers to the mainland's commitment that carbon dioxide emissions will not increase until 2030, and will gradually decrease after reaching the peak. "Carbon neutrality" refers to the total amount of greenhouse gas emissions directly or indirectly generated by enterprises, groups or individuals in a certain period of time, and then offsets the carbon dioxide emissions generated by itself through plant afforestation, energy conservation and emission reduction, etc., to achieve "zero emissions" of carbon dioxide.

Reach carbon peaks in 2021-2030, reduce carbon emissions by 2031-2045, and achieve carbon neutrality by 2045-2060. "Carbon peaking is a means, carbon neutrality is our real goal, and only carbon peaking can achieve carbon neutrality." Hou Baorong pointed out. In his view, the realization of carbon peaking affects the difficulty of carbon neutrality practice, the earlier the carbon peak is realized, the stronger the ability to achieve carbon neutrality, the lower the difficulty of carbon peak emission reduction, and the less pressure to reduce emissions.

China has long demonstrated its determination to achieve the "double carbon" goal, and on September 22, 2020, the 75th session of the United Nations General Assembly, China said it would adopt more favorable policies and measures and proposed the "3060" target. On December 12, 2020, we committed to reducing China's CARBON dioxide emissions per unit of GDP by more than 65% in 2030 compared to 2005. On January 25, 2021, at the World Economic Forum, it was proposed that China will strengthen the construction of ecological civilization, accelerate the adjustment and optimization of industrial structure, and advocate a green and low-carbon approach.

On July 24 this year, the central government issued a document, in the "State Council of the Communist Party of China on the Complete, Accurate and Comprehensive Implementation of the New Development Concept to Do a Good Job in Carbon Neutrality", which put forward five requirements, such as building a green and low-carbon circular development economic system, improving energy utilization efficiency, increasing the proportion of non-fossil energy consumption, reducing carbon dioxide emission levels, and improving the carbon sink capacity of ecosystems.

The mainland is the country with the largest construction area in the world, and it is also the world's largest producer and consumer of building materials. The annual demand for concrete, cement and other building materials reaches 100 million tons, and every ton of cement produced emits a ton of carbon dioxide, which has a lot of corrosion. In 2020, cement production emitted a total of about 1.23 billion tons of carbon dioxide. Carbon emissions from the cement industry account for 6% of the world's total carbon emissions, and the two major carbon sources for concrete and cement come from the combustion of carbon coal. According to statistics, every kilowatt-hour of electricity saved is equivalent to saving 0.4 coal and 0.99 grams of carbon dioxide. If the service of concrete is increased from 25 to 100 years through anti-corrosion technology, the emission of carbon dioxide will be reduced by 5 times.

"Extending the service life of these materials can significantly reduce global carbon dioxide emissions." Hou Baorong concluded.

China's steel industry carbon emissions accounted for the proportion of the country's total carbon dioxide emissions are increasing year by year, the current amount of carbon dioxide produced by steel accounts for 19.16% of the country's carbon dioxide emissions, and China's steel production accounts for 60% of the world's steel production, steel production process, carbon emissions from the combustion of coal and other electricity consumption, if you can reduce the combustion of coal and the consumption of electricity, carbon emissions will be greatly reduced.

Focus on the weak points of the material Using oxidative polymerization type coating anti-corrosion technology

So what exactly can corrosion protection technology do? And what should I do? Corrosion protection is generally divided into physical anti-corrosion, chemical anti-corrosion, electrochemical anti-corrosion and other means, of which paint anti-corrosion accounted for 66% of the share.

Coating method corrosion protection includes three categories: coating and spraying, coating and chemical conversion film. A protective layer is made on the metal surface to separate the metal from contact with the corrosive medium, thereby reducing corrosion. Coating is to coat organic and inorganic compounds on the metal surface, the commonly used method is to paint and plastic coating, spraying is through the spray gun or dish atomizer, with the help of pressure or centrifugal force, dispersed into uniform and fine droplets, applied to the surface of the coating method, mainly divided into arc spraying, plasma spraying, electrostatic spraying, manual spraying, etc.; Metal plating is a process that uses metal powder to form a coating on the surface of the workpiece, mainly including electroplating, hot plating, spray plating, seepage plating, chemical plating, mechanical plating, vacuum plating, etc.; Chemical conversion film is the use of chemical or electrochemical methods to form a stable compound film layer on the metal surface, according to the medium used in film formation, the chemical conversion film can be divided into oxide film, phosphate film, chromate film and the like.

According to the substances that constitute the protective layer of the coating method, it can be divided into two categories: non-metallic protective layer and metal protective layer, such as paint, plastic, fiberglass, rubber, asphalt, enamel, concrete, enamel, anti-rust oil, etc. as non-metallic protective layer, and the metal protective layer is plated with a metal or alloy on the metal surface as a protective layer to slow down the corrosion rate. The metals used as protective layers are usually zinc, tin, aluminum, nickel, chromium, copper, cadmium, titanium, lead, gold, silver, palladium, rhodium and various alloys.

The first thing in anti-corrosion is to grasp the key points and find out which place is the most seriously corroded. It is necessary to use new thinking and new technologies to solve the problem of the short version. "As early as 14 years ago, the Qingdao Port Authority was the first to achieve corrosion protection in the splash area on the mainland." Hou Baorong pointed out, "We have also done a project to alleviate the problem of corrosion for the Port Authority, and recently signed an agreement with the Port Authority, and we will cooperate more and more with the Port Authority in the future."

In addition, oxidative polymerization type cladding anti-corrosion technology is also a very important means. This technology can be used to solve the problem of corrosion of special-shaped parts of the atmospheric area, and other problems will be solved after these shortcomings are solved. At present, this technology has been successfully applied to the Wenchang Launch Base in Hainan, and all 8 launch plans have used this technology.

China Tianyan's anti-corrosion operation is also worth paying attention to, and Hou Baorong's team has tracked and monitored and protected all the corrosion problems it may produce. "We want to make reinforced concrete a big deal to solve the problem of corrosion. In terms of wave splash protection technology, we can extend the life of steel clothing very well, including special-shaped parts of steel structure clad anti-corrosion technology, and the overall steel structure life extension. Hou Baorong pointed out.

1 ton of carbon dioxide is released for every ton of cement produced, and 1.83 tons of carbon dioxide is released for every ton of steel produced. New corrosion protection technologies are one of the ways to achieve the goal of "double carbon". Government departments should pay more attention to corrosion phenomena and support anti-corrosion technology, enterprises should also take the initiative to green, active, accurate corrosion as a major event, scientific research institutions need to continue to innovate, the use of efficient technology for corrosion prevention, to extend the life of reinforced concrete, reduce carbon emissions.

"The road is obstructive and long, the line is coming, the line is not broken, the future can be expected!" For the future, Hou Baorong is full of confidence.