###### Abstract
The hybrid composite discharge electrode exhibited a lower corona onset voltage than conventional metal electrodes, and the corona discharge was more uniform at comparable power levels. A two-stage electrostatic precipitator, designed for the removal of particles and acidic droplets (for example, HF, HCl, HNO\({}_{3}\), and H\({}_{2}\)SO\({}_{4}\)) from corrosive gasses, discharged from the wet-etching technologies in semiconductor and optoelectronic industries, and from explosive gasses, as developed by [PERSON] et al. (2016). The precharger stage consisted of ion injectors with clean air sheath, placed outside the main gas flow, and constructed from carbon brush. The carbon electrodes were more resistant to the corrosive atmosphere than those made of metal. The collection efficiency for PM2.5 particles, achieved by this device, was between 89.5% and 99.5%, depending on the brush electrode depth, by a voltage applied to the carbon brush emission electrodes of \(-\)23 kV, and the exhaust gas flow rate of 600 L/min. [PERSON] and [PERSON] (2017) considered the problem of mechanisms of the corrosion of electrodes in electrostatic precipitators. The authors identified the following types of corrosion specific to electrostatic precipitators, from which the most important are the following:  
Uniform attack--this appears in the case the electrode has a direct contact with acids, caustics, or other corrosive liquids separated from the gas on a large surface of the electrode. The most susceptible to these attacks are collection plates, gas distribution baffles, hoppers, shells, roof, and isolator supports, and particularly the surfaces, which are locally cooled due to imperfect thermal isolation. Pitting--this is an intense deep corrosion in small areas (points), particularly in the breakdowns of protective coating. The most vulnerable to this type of corrosion are discharge electrodes and rappers, and places through which cold air is drawn in. Stress corrosion--this occurs in places loaded with high tensile stress in the presence of corrosive atmosphere. The discharge electrode frames are susceptible at their bents to this type of corrosion due to microcells formed in the material in the fabrication process. Crevices corrosion--this is a type of corrosion occurring in tight gaps between two different parts in contact, for example, under gaskets, seals, washers, and screws, or inside cracks and seams. This type of corrosion may occur in all connections of different parts in an electrostatic precipitator. Intergranular corrosion--this appears along material grain boundaries, particularly those formed due to material stress during cooling after welding. This type of corrosion may occur in the shells and roof, as well as in collection or discharge electrodes. Fatigue corrosion--this results from a cyclic load or stress in a corrosive atmosphere. This fatigue leads to the formation of micro or macro cracks. The rappers, rapper anvils, particularly in welded areas, or hangers of collection plates are loaded by excessive vibration during rapping or the discharge electrodes. Impingement attack--in the case of electrostatic precipitators, this is a process of scouring the metal surfaces exposed to the flowing abrasive media, leading to its erosion or surface attack through the scale, which are the corrosive products. Fretting corrosion--this is the high frequency vibration of the collection and discharge electrodes during their rapping, which leads to metal fit erosion as an effect of friction. Galvanic action--this corrosion occurs in a junction between two metals of different electrochemical potentials in the galvanic series. This localized metal erosion occurs particularly in the connections of discharge electrodes to a high voltage source. In many practical cases all the mentioned mechanisms operate simultaneously, providing a synergistic effect in the electrode's failure, and the final electrode degradation reasons are difficult to distinguish.