dimanche 9 novembre 2014
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Taking A Look At Perterbilt Chrome
The plating operation involves covering a part of a greater or lesser thickness of 0.5 microns (decorative chromium) 1/10 mm ground (hard chromium). The required qualities to surface layer is not the same as the intended applications are usually two kinds of plating. It provides shiny surfaces polished chromium decorative chromium aims (Perterbilt chrome). It is used for example for the bumper and door handles.
In case of breakage or porosity of protective film, the underlying metal corrodes in a localized manner and very intense (remember, for example, the degradation of many chromium metal parts in cars with a few decade of life). It is essential, accordingly, an adequate thickness of plating, the minimum value of which depends on the metal to be protected, the environmental conditions and by economic factors.
Deposition of chromium may be deposited directly onto workpiece according to its use. For cylinders it is advisable to perform a sub-layer of nickel 20 microns to limit corrosion. You should know that the chromium deposit has a low cathode efficiency (15%) and cathode occurs a release of hydrogen which weakens the steel and reduces resistance to fatigue. Degassing treatment is to return to mechanical characteristics of part.
Chromium layer can applied for decorative purposes, to provide protection against corrosion or to increase the hardness of surface. Parts subjected to plating, as a rule, through the following steps: Cleaning to remove stubborn dirt. Fine cleaning to remove contamination. Pretreatment (varies depending on base material). Placement in a bath with a saturated saline and temperature equalization. Connecting the power and shutter speed to obtain desired thickness
It can be accomplished by plating the physical vapor deposition (PVD). The most promising technique is probably the magnetron sputtering (PCM). This operation happens in a vacuum chamber containing argon or other inert gas under very low pressure (a few hundredths). A target composed of a metal M is raised to a sufficiently high negative voltage to electric field thus created can ionize the atmosphere in its vicinity.
The process of traditional chromium (in use in furnishing field) provides immersion of workpiece to be plated in a series of baths. In a first series the workpiece is degreased and cleaned. Among these there are the main ones: electrolytic solution of caustic soda, the electrolytic solution of hydrochloric acid with related washing baths. The main bathroom (where the piece rest for longer) is that of electrolyte solution of nickel. In fact, before the chromium coating, it is important to create a layer of nickel that uniform as possible to metal surface at the microscopic level. After further washing takes place in water-bath of electrolyte solution for chromium.
By applying a magnetic field in addition to electric field perpendicular, it significantly increases the density of plasma which is formed around the target, the deposition rate can then reach a commercially acceptable value of order of 1 micron / min. Deposits made by PCM are much less cracked and much more compact than those made by electroplating but they are also much softer. The presence within confines of traces of other elements such as oxygen, nitrogen, carbon, can correct this defect and even achieve much higher hardness.
In some cases, chromium is used for repair parts by increasing the mating surface in case of loosening planting. At the present time can used as a "garage" or "cold" alternative to plasma spraying metal parts of similar material. Typical are the following solutions for plating: Hexavalent chromium, whose main ingredient - chromic anhydride. Trivalent chromium, whose main ingredient - chromium sulfate or chromium chloride. Trivalent chromium bath is rarely used because of constraints imposed on the color, brightness and thickness of coating.
In case of breakage or porosity of protective film, the underlying metal corrodes in a localized manner and very intense (remember, for example, the degradation of many chromium metal parts in cars with a few decade of life). It is essential, accordingly, an adequate thickness of plating, the minimum value of which depends on the metal to be protected, the environmental conditions and by economic factors.
Deposition of chromium may be deposited directly onto workpiece according to its use. For cylinders it is advisable to perform a sub-layer of nickel 20 microns to limit corrosion. You should know that the chromium deposit has a low cathode efficiency (15%) and cathode occurs a release of hydrogen which weakens the steel and reduces resistance to fatigue. Degassing treatment is to return to mechanical characteristics of part.
Chromium layer can applied for decorative purposes, to provide protection against corrosion or to increase the hardness of surface. Parts subjected to plating, as a rule, through the following steps: Cleaning to remove stubborn dirt. Fine cleaning to remove contamination. Pretreatment (varies depending on base material). Placement in a bath with a saturated saline and temperature equalization. Connecting the power and shutter speed to obtain desired thickness
It can be accomplished by plating the physical vapor deposition (PVD). The most promising technique is probably the magnetron sputtering (PCM). This operation happens in a vacuum chamber containing argon or other inert gas under very low pressure (a few hundredths). A target composed of a metal M is raised to a sufficiently high negative voltage to electric field thus created can ionize the atmosphere in its vicinity.
The process of traditional chromium (in use in furnishing field) provides immersion of workpiece to be plated in a series of baths. In a first series the workpiece is degreased and cleaned. Among these there are the main ones: electrolytic solution of caustic soda, the electrolytic solution of hydrochloric acid with related washing baths. The main bathroom (where the piece rest for longer) is that of electrolyte solution of nickel. In fact, before the chromium coating, it is important to create a layer of nickel that uniform as possible to metal surface at the microscopic level. After further washing takes place in water-bath of electrolyte solution for chromium.
By applying a magnetic field in addition to electric field perpendicular, it significantly increases the density of plasma which is formed around the target, the deposition rate can then reach a commercially acceptable value of order of 1 micron / min. Deposits made by PCM are much less cracked and much more compact than those made by electroplating but they are also much softer. The presence within confines of traces of other elements such as oxygen, nitrogen, carbon, can correct this defect and even achieve much higher hardness.
In some cases, chromium is used for repair parts by increasing the mating surface in case of loosening planting. At the present time can used as a "garage" or "cold" alternative to plasma spraying metal parts of similar material. Typical are the following solutions for plating: Hexavalent chromium, whose main ingredient - chromic anhydride. Trivalent chromium, whose main ingredient - chromium sulfate or chromium chloride. Trivalent chromium bath is rarely used because of constraints imposed on the color, brightness and thickness of coating.
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