Question: Is metal on metal deposition a reasonable way to prevent corrosion?
About the article "Electrochemistry", section "Coating".

Candidate passages:
A sacrificial metal is a metal used as a sacrificial anode in cathodic protection that corrodes to prevent a primary metal from corrosion, galvanization or rusting. 
Metal dusting is a catastrophic form of corrosion that occurs when susceptible materials are exposed to environments with high carbon activities, such as synthesis gas and other high-CO environments.
The corrosion manifests itself as a break-up of bulk metal to metal powder.
The suspected mechanism is firstly the deposition of a graphite layer on the surface of the metal, usually from carbon monoxide (CO) in the vapour phase.
This graphite layer is then thought to form metastable M3C species (where M is the metal), which migrate away from the metal surface.
However, in some regimes no M3C species is observed indicating a direct transfer of metal atoms into the graphite layer. 
Some metal tetrahydroborates transform on heating to give metal borides.
When the borohydride complex is volatile, this decomposition pathway is the basis of chemical vapor deposition, a way of depositing thin films of metal borides.
For example, zirconium and hafnium diborides, ZrB2 and HfB2, can be prepared through CVD of the tetrahydroborates Zr(BH4)4 and Hf(BH4)4:M(BH4)4 → MB2 + B2H6 + 5H2 Metal diborides find uses as coatings because of their hardness, high melting point, strength, resistance to wear and corrosion, and good electrical conductivity.
The diboride films can be deposited on a variety of substances including glass, copper, aluminum, and steel. 
Attempts to save a metal from becoming anodic are of two general types.
Anodic regions dissolve and destroy the structural integrity of the metal.
While it is almost impossible to prevent anode/cathode formation, if a non-conducting material covers the metal, contact with the electrolyte is not possible and corrosion will not occur. 
Metal dusting is "a catastrophic form of corrosion that occurs when susceptible materials are exposed to environments with high carbon activities."
The corrosion manifests itself as a break-up of bulk metal to metal powder.
The suspected mechanism is firstly the deposition of a graphite layer on the surface of the metal, usually from carbon monoxide (CO) in the vapour phase.
This graphite layer is then thought to form metastable M3C species (where M is the metal), which migrate away from the metal surface.
However, in some regimes no M3C species is observed indicating a direct transfer of metal atoms into the graphite layer.
The temperatures normally associated with metal dusting are high (300–850 °C).
From a general understanding of chemistry, it can be deduced that at lower temperatures, the rate of reaction to form the metastable M3C species is too low to be significant, and at much higher temperatures the graphite layer is unstable and so CO deposition does not occur (at least to any appreciable degree).
Very briefly, there are several proposed methods for prevention or reduction of metal dusting; the most common seem to be Aluminide Coatings, alloying with copper and addition of steam.
There is a significant amount of literature in existence that describes proposed mechanisms, prevention methods etc.
There is also a good summary of metal dusting and some prevention methods in 'Corrosion by Carbon and Nitrogen - Metal Dusting, Carburisation and Nitridation'