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Many thanks to Prof. M.A. El Khakani and INRS‐ Centre Énergie, Matériaux Té telecommunications for the detailed inspection of the electrodes. In the test report, XRD, SEM, and Ra tests are carried out on the MMO electrode. These test items give an intuitive explanation for some theoretical indicators of the electrode.
1.XRD
From the analysis results of XRD, it can be concluded that the crystal structure of our electrode meets the requirements of the coating material, and the surface is thermally oxidized to form a precious metal oxide active coating of RuO2-IrO2-TiO2 rutile phase solid solution.
In the comparison results of XRD, it is considered that the Ti peak exists in the sample QH-B, and the detection is considered to be that the overall coating is thinner. But from our point of view, this result is caused by the different substrate processes adopted by the two parties. We adopt the physical sandblasting process, which uses compressed air as power to form a high-speed jet beam, and sprays brown corundum 28-32 mesh (0.6-0.55mm) to the surface of the workpiece to be treated at a high speed, so that the surface of the workpiece can obtain a certain degree of cleanliness and roughness, thereby increasing the adhesion of the coating to the base layer.
However, the increase of roughness will cause less coating on the tip of the surface during the brushing process, and Ti peaks will appear in the XRD detection. The MMO produced by our company has reached the factory standard in the coating thickness test at the factory.
In the process of electrode processing and use for more than 30 years, we have found that compared with the smooth electrode surface, the rough electrode surface increases the bonding
strength between the coating and the substrate, and also reduces the consumption rate of the electrode coating, thereby prolonging the electrode coating. service life. The basis of electrode electrolysis is the active quantity and quality of the active coating, the increase of the effective electrolysis area, and the electrolysis efficiency of the active coating is the foundation of electrolysis.
2.SEM
It can be seen from the SEM images of 10 μm and 2.5 μm that the coating on the electrode surface shows a “parched-earth-like” crack state.
The 50μm picture of SEM shows that the crack state of our electrode is mainly concentrated on the concave surface of the titanium plate; at the peak, it appears as "protruding pebbles". This phenomenon can be corroborated with the Ti peak of XRD.
It can also be seen in the 500μm picture of SEM that the KIG-B electrode has a large roughness, which greatly increases the specific surface area of the substrate and greatly increases the actual effective electrolysis area of the electrode.
For the our electrode, partial detachment occurs, which is a normal phenomenon in the use of MMO electrodes. During the use of the electrode, the coating will gradually fail and fall off, eventually reaching the limit of use of the MMO electrode and reaching the service life of the electrode.
3.Surface Roughness
The test gives the average surface roughness (Ra) of CARV-1, and it can be seen that its uncoated surface roughness is much lower than ours. We adopt the physical sandblasting process, and spray brown corundum 28-32 mesh (0.6-0.55mm) to the surface of the workpiece to be treated at high speed, and its roughness is much larger than that of the titanium substrate surface of CARV-1. This is also corroborated with the SEM 500 μm KIG-B picture.
We have already explained the problems in the above three aspects of testing.
Different processing techniques lead to different surface morphologies, which can be shown intuitively from the detection results of SEM and XRD. These two indicators are only a part of the theoretical indicators of electrode performance. The two indicators of electrode electrolysis service life and electrolysis efficiency are not shown in the test report. During the research and development of the new electrode, the surface morphology of a single tortoise crack cannot indicate that it is a good electrode at all.
Our company has been deeply engaged in the field of titanium electrode processing and production for more than 30 years, and has accumulated rich practical experience under various conditions of use. Our company currently adopts physical sandblasting-automatic brushing- thermal oxidation process for the production and processing of MMO. After the surface is thermally oxidized, a precious metal oxide active coating of RuO2-IrO2-TiO2 is formed, and the chlorine-containing electrolyte is electrolyzed under the action of an electric field. , to produce chlorine-containing disinfection substances to achieve a certain bactericidal effect. Our company is also using this technology to develop a series of electrolytic sterilization and disinfection equipment, which are used in the fields of medical device disinfection, food hygiene and safety, environmental disinfection, surface disinfection, air disinfection, water disinfection and other fields. At the same time, it is also the participating drafting unit of relevant Chinese national standards.
