Germany invents new process to directly produce alloys from metal oxides

Source: Xinhua News Agency, Beijing, September 23- German researchers recently reported in the latest issue of the British journal Nature that they have invented a new alloy smelting process that can instantly turn solid metal oxides into block alloys. This technology does not require refining metals and melting or mixing them, which helps reduce greenhouse gas emissions and save energy. Researchers at the Max Planck Institute for Sustainable Materials in Germany have successfully produced low expansion alloys by using hydrogen instead of carbon as a reducing agent to extract metals and form alloys at temperatures far below their melting points. Low expansion alloys are composed of 64% iron and 36% nickel, and can maintain a relatively constant volume over a considerable temperature range, making them widely used in industry. Researchers mixed iron oxide and nickel oxide in the required ratio for low expansion alloys, and used a ball mill to mix them evenly before pressing them into small round cakes. They were then heated to 700 degrees Celsius in a furnace and hydrogen gas was introduced. This temperature is not sufficient to melt iron or nickel, but it is sufficient to reduce the metal. Testing shows that the processed block metal exhibits typical characteristics of low expansion alloys and has better mechanical properties due to its small grain size. Because the finished product is in block form rather than powder or nanoparticles, it is easy to cast and process. Traditional alloy smelting is divided into three main steps: first, the metal oxides in the ore are reduced to metal with carbon, and then different metals are melted and mixed after decarburization. Then, thermal mechanical processing is carried out to adjust the microstructure and make the alloy have specific properties. These steps consume a huge amount of energy, and the process of reducing metals with carbon produces a large amount of carbon dioxide. The carbon emissions of the metallurgical industry account for about 10% of the global total. Researchers say that the byproduct of reducing metals with hydrogen is water, resulting in zero carbon emissions. The simple process also makes the new technology have enormous energy-saving potential. However, the purity of iron oxide and nickel oxide used in the experiment is relatively high, and the efficiency of using natural ores as raw materials remains to be verified. Moreover, the production and application cost of hydrogen gas itself is relatively high. The research team is trying to increase the reaction temperature to reduce the amount of hydrogen used, hoping to further reduce energy consumption.