Advantages - Zinga Versus Metallizing
Zinga versus Metallizing
Offers a cathodic protection throughout the layer, comparable to the cathodic protection of hot dip galvanising (Prof. Defrancq - University of Ghent).
Offers a cathodic protection throughout the layer.
A layer of zinc salts slowly builds up on the ZINGA surface. This creates a barrier protec- tion for the metal substrate. Next to this, a supplementary barrier protection is provided by the binder in ZINGA. The binder reduces the disintegration of the zinc.
The 100 % zinc in the thermal zinc spray system is a naked zinc, without the barrier protection of the zinc particles in ZINGA.
Does not need a topcoat. A single layer of ZIN- GA is in itself a Duplex system offering on one side an ACTIVE-CATHODIC protection, on the other side a PASSIVE-BARRIER protection.
Has porosities and the zinc in a metallisation layer is a naked zinc, therefore it is neces- sary to apply a stabilisation coating before applying one or two topcoats.
Flexibility and Brittleness
ZINGA containing 96 % of zinc remains a flexible layer, and resists to mechanical shocks by being compressed. There is no risk of disbonding (not even around the impact) within a multiple layer of ZINGA. It will never show adhesion failures. Even on thin metal ZINGA remains always the same flexible layer.
The probability exists that abrasion and/or impact (e.g. road debris), due to the brittle- ness of thermal spray coatings, results in a high incidence chipping and crack propa- gation, thereby undermining the integrity of the coating surface. Excessive cracking, at any DFT, when applied to thin/flexible metal surfaces. As a result, the thermal zinc spray flakes off and/or cracks due to metal surfa- ce flexure, thereby undermining the integrity of the coating coverage.
ZINGA will not break down at sharp corners due to its flexibility.
Thermal spray coatings tend to break down at sharp corners creating target corrosion sites.
A polymerised ZINGA layer will re-liquidise upon contact with ZINGA, even after 20 years.
After application, the zinc will not re-liquidise upon contact with a new layer.
ZINGA is applied on a clean and rough surface to be obtained by a blasting Sa 2 ½, 12.5 µm with the right blasting material. A complete cle- aning to the white metal is not required, a cer- tain degree of adhering rust can be accepted, it will even increase the binding of the ZINGA to the metal surface.
The Thermal Spray process requires an ex- tremely clean white blast metal surface for a proper binding 0integrity. Extreme and absolute dry surface is required. Fully cleaned surfaces are critical to the Thermal Spray process. Moreover, white cleaning is difficult to obtain over large surface areas. The clean white metal grit blast process (to SSPC-SP-5) can also produce component distortion. Conventionally it is advised to use the Thermal Spray within 30 minutes in the open air and within 6 hours in covered areas.
A ZINGA-coating can be applied everywhere under normal conditions, regardless of tempe- rature and humidity. It does not require highly qualified personnel.
Thermal Spray coatings are very labour in- tensive and have to be performed by highly trained technicians in a workshop.