Passive film, is adhered film renders metals or alloys to getting more noble potential compared to their status before this passivation. The passive film modtly will be oxide, other passive film can be from sulphide, as the case of silver sulphide (tarnishing).

Most of the metals or alloys have their tendency to form the passive film which depends on the nature of the metal (alloys) controlled by Wagner theor y (rate of oxide film formation in air on different metals (alloys) .

The more inert the metal, the more the strong the passive film formed (compared for example gold oxide to iron oxide).

If we move to electrolytic solution and speaking about electrolytic bath, for decorative reasons or for other specific purposes. In that case these oxides acting as decorative in first place and as protective as well. Most of the process is done by the known anodic coloring, which involves impeding a color in the oxide film when it is formed during passivation, once the required color developed, a process to keep this decorative film is applied to seal this film. Passivation is mostly used in place of oxide film formation, but not all of oxide film are formed by passivation. Forgot to say that passive film, the metal or alloy shows inertness (i.e., the current is not increasing drastically while changing the potential). I hope this help.

thank you so much that was a great help. just to conclude I would say that the passive layer can be used interchangeably with the oxide layer if they form as a result of interaction with O2 . However, if the passive layer formed with other element such as the case of Ni then it is passive layer not oxide layer because it does not have O2. The formation of the passive layer depends mainly on Wanger theory.

AA Rana,

I suggest you read some of the review papers on The Point Defect Model. Search for "the history of the point defect model for passive films". It should give a more fundamental understanding of passivation.

Oxide layers are the layers formed due to the reaction of materials surface with the oxygen as simple as that..however the formation of this layer is depends on various factors such as materials composition, atmosphere, the effective interaction with the oxygen. for example, when u slide Al surface there will be formation of AlO on the wear track which has a tendency to increase the friction force, in some article they have said like decrease in the friction force so it is contradictory...passive layer is layer which often find in the solid lubricant materials...so during the sliding these materials tends to adhere to the wear track and form as a film....for example you can take PTFE ....

Tarnish is a thin layer of corrosion that forms over copper, brass, silver, aluminum, magnesium and other similar metals as their outermost layer undergoes a chemical reaction. Tarnish does not always result from the sole effects of oxygen in the air. For example, silver needs hydrogen sulfide to tarnish, although it may tarnish with oxygen over time. It often appears as a dull, gray or black film or coating over metal

Most of the Oxide layers are passive because oxide bonds are very strong. It can be broken in reducing atmosphere with the presence of Hydrogen or CO. However, these reducing agents can convert the oxides of lower oxidation state and conversion of lowest oxidation state further into elements will require huge energy.

Passivation is mostly used in the place of oxidation film but not all oxide films are passivation. However, if the passivation formed with other elements such as the case of Ni then it is passivation layer not oxidation layer because it does not have O2 oxygen molecule.

Passivation, in physical chemistry and engineering, refers to a material becoming "passive," that is, less affected or corroded by the environment of future use. Passivation involves creation of an outer layer of shield material that is applied as a microcoating, created by chemical reaction with the base material, or allowed to build from spontaneous oxidation in the air. As a technique, passivation is the use of a light coat of a protective material, such as metal oxide, to create a shell against corrosion. Passivation can occur only in certain conditions, and is used in microelectronics to enhance silicon.

Oxide films are likely to inhibit surface diffusion, and the preferential absorption of oxygen or oxide film formation at crack tips will inhibit will absorption of embrittling metal atoms. It is used in advance machining technology likely name as oxide film laser lithography using EMM is based on irradiation of annodically formed oxide film particularly for the fabrication of multilayer structures.

In my opinion, principally they are same except some uses are different. Passivation is useful in corrosion and coating study, oxide films are mostly used in the advance machining technology. Both can be used in microelectronics application.