22-12-2012, 06:43 PM
Electropolishing
[attachment=45051]
INTRODUCTION
Electropolishing, also known as electrochemical polishing or electrolytic polishing (especially in the metallography field), is an electrochemical process that removes material from a metallic workpiece. It is used to polish, passivate, and deburr metal parts. It is often described as the reverse of electroplating. It may be used instead of abrasive fine polishing in microstructural preparation.
Electropolishing Process:
Electropolishing is a process by which metal is removed from a work piece by passage of electric current while the work is submerged in a specially-designed solution. The process is essentially the reverse of electroplating. In a plating system, metal ions are deposited from the solution onto the work piece; in an electropolishing system, the work piece itself is dissolved, adding metal ions to the solution.
The reaction states that metal is dissolved from the anodic electrode, passing into the solution to form a soluble salt of the metal. All of the components of stainless steel, namely the iron, the chromium, and the nickel, undergo this reaction simultaneously, producing the controlled smoothing of the surface. Several side reactions also occur, creating byproducts which must be controlled in order to produce the highest possible quality of electropolishing.
The quantity of metal removed from the work piece is proportional to the amount of current applied and the time. Other factors, such as the geometry of the work piece, affect the distribution of the current and, consequently, have an important bearing upon the amount of metal removed in local areas. Figure 2 illustrates both high and low current density areas of the same part and notes the relative effect of electropolishing in these two areas.
[attachment=45051]
INTRODUCTION
Electropolishing, also known as electrochemical polishing or electrolytic polishing (especially in the metallography field), is an electrochemical process that removes material from a metallic workpiece. It is used to polish, passivate, and deburr metal parts. It is often described as the reverse of electroplating. It may be used instead of abrasive fine polishing in microstructural preparation.
Electropolishing Process:
Electropolishing is a process by which metal is removed from a work piece by passage of electric current while the work is submerged in a specially-designed solution. The process is essentially the reverse of electroplating. In a plating system, metal ions are deposited from the solution onto the work piece; in an electropolishing system, the work piece itself is dissolved, adding metal ions to the solution.
The reaction states that metal is dissolved from the anodic electrode, passing into the solution to form a soluble salt of the metal. All of the components of stainless steel, namely the iron, the chromium, and the nickel, undergo this reaction simultaneously, producing the controlled smoothing of the surface. Several side reactions also occur, creating byproducts which must be controlled in order to produce the highest possible quality of electropolishing.
The quantity of metal removed from the work piece is proportional to the amount of current applied and the time. Other factors, such as the geometry of the work piece, affect the distribution of the current and, consequently, have an important bearing upon the amount of metal removed in local areas. Figure 2 illustrates both high and low current density areas of the same part and notes the relative effect of electropolishing in these two areas.