Electrochemical Method Of Preparation Of Cnx Materials Experiments Discussed

Material is the foundation of society development. Historians divide human history into the Stone Age, Bronze Age, Iron Age, and this division is clearly based on the hardness and toughness of the material used by human. With the development of society and technology, the requirement on the hardness of material has been gradually enhanced. After the industrial revolution, iron and ferroalloys were widely used, however, with hardness of workpiece increasing; high hardness workpiece processing had become an issue that people have to face. Diamond, which is the hardest natural mineral, is no doubt an excellent choice for processing of high hardness workpiece, but as the scarcity of natural diamond and the harsh experimental conditions for synthesis diamond, the price of them is extremely expensive. So to find other super hard materials, replacing diamond and synthesis diamond becomes the people's target. In 1989, U.S. scientists Liu and Cohen theoretically predictedβ-C3N4 base on the structure ofβ-Si3N4, and the result show that this material could be as hard as diamond, besides that the new material also has a series of unique mechanical, optical and tribological properties. This prediction Attracted wide attention of physicists, chemists and materials scientists. Since then, many experimental and theoretical studies have been done on this material. This paper reviews the history and status quo of carbon nitride's the theoretical study and experimental study. After contrasting the reported synthetic methods, considering the degree of difficulty of industrialization we chose the method of electrochemical deposition of carbon nitride.According to the reported research on electrochemical deposition of carbon nitride, we designed the experiment plan and instrument, conducted effective solutions of the precursor ratio, thermal reactor, impurities, and many other issues, and achieved carbon nitride films with both quality surface morphology and crystal structure. Meanwhile, the strange phenomenon occurred during the electrochemical deposition were solved by adding acetic acid into the precursor solution, base on the investigating of experimental mechanism. The results show that with the addition of acetic acid, crystalline quality of the product has been greatly improved and the dendrite crystal growth appeared, which is the typical phenomenon of crystal growth. Finally, we also did comparative research on the impact of current density on the film quality. By changing the experimental current density, we get the 4 test samples, the results show that the current density influences the film quality significantly. When the operating current density is less than 40mA/cm2, the XRD patterns of the samples does not appear diffraction peaks other than Si (100), illustrating that there was not crystal structure of carbon nitride on the surface. When the current is greater than 50mA/cm2, the diffraction peaks in XRD patterns of the samples began to appear, and these peaks coincide with the theoretical predictions excellently. When the current density was 70mA/cm2, the diffraction peaks in XRD patterns become much penetrating, however when the current density rose to 75mA/cm2, the quality of the films declined, indicating that 70mA/cm2 should be better operating current density. The nitrogen to carbon ratio of the film is 0.94, very close to the theoretical value of 1.33. X-ray diffraction peaks fit with the theoretical predictions of the diffraction peaks of carbon nitride excellently; whose errors are less than 1%, a variety of analysis profiles showed that the samples contain carbon nitride crystal structure.