Essentially, this is a steel sheet coated with an alloy consisting (by weight) of 55% Aluminum 43.4% Zinc and 1.6% Silicon. In this product, the strength of steel, the barrier protection of Aluminum and the cathodic protection of Zinc, all combine in a complimentary manner, making the product extremely durable and economical.

MRM has pioneered this unique technology in the African continent by putting up the first state-of-the-art manufacturing facility.

PRODUCT DEVELOPMENT HISTORY

Aluminum – Zinc coated steel is the outcome of considerable research conducted at Bethlehem Steel Co. – U.S.A around the 1960’s.

Experiments were tried out on the basis of salt spray tests and at this coating composition the product was found to give the best results.

In 1972, the company begun making the new product on a commercial scale under the name ‘Galvalume’.

The Zinc then serves as the sacrificial anode and gets consumed in preference to the steel and hence provides sacrificial or cathodic protection. The rate of corrosion that the Zinc undergoes while protecting the steel is considerably lower than that of steel on its own. In this way, a thin coating of Zinc applied to steel, protects it for a long time.

ECONOMICS

Zinc coated steel sheets, offer a unique combination of strength, durability, malleability, recyclability and cost effectiveness. This makes it an ideal, material for low cost housing. Galvanized roofing sheets are widely used as the most economical roofing material throughout the world.

ENVIRONMENTALLY FRIENDLY

Zinc-coated steel is an environmentally responsible choice. Recent research is shedding light on the role of Zinc in our environment. Zinc is an integral part of our environment and exists naturally in rock, soil, air and water. Zinc is also an essential element for all life, from humans and animals to plants and micro-organisms.

Hence, while relatively small quantities of Zinc wash off from coatings exposed to the outdoor environment, this Zinc is usually not bioavailable and has little impact on the surrounding ecosystem.

CORROSION RESISTANCE

With 55% Aluminum-Zinc coated Steel (55% AL-ZN), in addition to the cathodic protection provided by the Zinc, there is the supplementary barrier protection of Aluminum as well.

Aluminum reacts with atmospheric oxygen to form Aluminum Oxide. This film of Aluminum Oxide is very stable in nature and provides protection to the steel even at elevated temperatures.

The corrosion resistance of Aluminum, can be further investigated by examining the coating structure, of 55% Aluminium-Zinc coated steel.

The structure consists of an overlay and an intermetallic layer. The overlay has an Aluminum rich matrix (which comprises about 80% volume) with a Zinc rich network (about 20% volume) interspersed with occasional Silicon particles. However at no point in the structure is there complete absence of either Aluminum or Zinc.

During the early stages of atmospheric exposure, the Zinc-rich network corrodes, but fills up with corrosion products, which stifle the corrosion process. The circuitous nature of this Zinc-rich network is a key factor in providing excellent corrosion resistance which has become the hallmark of 55% AL-ZN coated sheets.

OUTSTANDING BENEFITS

Excellent corrosion resistance (which makes the product extremely durable), and high heat reflectivity are the two major benefits of 55% AL-ZN coated sheet.

1 LONG LIFE:

The exceptionally long life of 55% AL-ZN coated sheet has been demonstrated in numerous case histories in all climatic and environmental conditions (see illustration). Compared to an ordinary galvanised sheet, the 55% AL-ZN coated sheet has demonstrated a life of upto 4 times longer.

2. HEAT REFLECTION

55% AL-ZN sheet has excellent heat reflectivity in operating temperatures of upto 315 degrees centigrade. The shiny bright surface and the inherent fine spangle are responsible for its excellent heat reflection.

In contrast to galvanised sheets, both initially have a shiny surface. However, the galvanised sheet loses its shine sooner, whereas the 55% AL-ZN surface retains the same look over a considerably long period. This ensures continued heat reflectivity of the AL-ZN sheet providing cooler temperatures of upto 3 degrees compared to ordinary galvanised sheet.

ECONOMICS

The tremendous long life of the product coupled with the benefit of cooler interiors makes the product an excellent economic choice for the construction industry.