Furnascote

Refractory Coating

General

Furnascote is the-collective name for a series of refractory coatings designed to protect the bricks, monolithics, castables and steel shells in furnaces, boilers and various high temperature vessels.

Furnascote refractories are characterised by a very high content of zirconia (as 62.9% ZrO₂) which imparts extremely high resistance to the aggressive environments typically encountered at temperatures up to 1900°C. Furnascote has better adhesion than most conventional zirconia based refractories.

The Two Main Furnascote Types

NON-VIT is the versatile, general purpose product. HI-GLAZE is used as a slag resistant finish to NON-VIT in annealing furnaces, spouts and funnels.

A 3mm protective layer of Furnascote can typically increase the working life of any underlying refractory by a factor of two to four times. Furnascote is supplied in the form of a powder which is mixed with cold water to the consistency of a paste, cement or slurry prior to application by trowel, brush or spray.

Main Uses for Furnascote

• To reduce the effects of thermal shock.
• To protect refractories against the aggressive effects of burning fuel oil, gas and solid fuels.
• To produce a gas tight surface and minimise energy losses.
• To reduce spalling.
• To eliminate cracking.
• To reduce slag adhesion.
• Generally, to increase the working life of furnaces and reduce the costs of maintenance shut downs.

Furnascote is used regularly in the following industries and processes

• Aluminium
• Brass and Non - ferrous
• Ceramics and Pottery
• Chemical
• Fertilizer
• Natural and Town Gas
• Iron and Steel
• Marine Shipping
• Nuclear Energy
• Petroleum
• Pulp and Paper
• Sugar Refining

Preparation

Furnascote should only be applied to sound, clean surfaces. Old refractory surfaces must be thoroughly cleaned with a scraper or wire brush removing all loose pieces. Any glassy surfaces should be roughened with an abrasive disc. Cracks and holes should be cleaned out then filled with a cement of NON-VIT.

Mixing

Mix Furnascote with cold water to a smooth, creamy consistency as follows :

Mix Form	Litres of Water per 25 Kg	Method of Application	Thickness of Coating
NON-VIT
Cement	3 litres	Trowel	1 to 3 mm
Paste	4 litres	Spray	0.5 to 3mm
Slurry	3.75 litres	Brush	0.25 to 2mm
HI-GLAZE
Paste	4 litres	Spray	0.25 to 3mm
Slurry	3.75 litres	Brush	0.25 to 3mm

Use a mechanical stirrer. Allow to stand after mixing for at least 1 hour then re-mix briefly.

Application

Using a brush, trowel or spray, coat the furnace walls, hearth, ceiling, bridges etc. to a thickness of 1 to 3mm as required. After an hour, further coats of NON-VIT or HI-GLAZE may be applied. The mix should be stirred every few minutes during application to prevent settling of heavy ingredients. For spray application, use a gun suitable for textured paints fitted with a gravity fed hopper. Nozzle = 4 to 6 mm, air pressure at 80 to 100 p.s.i.

Drying

The coating must be absolutely dry before firing. Under ambient temperatures, allow approximately 6 hours per 1mm thickness of coating. Warm air and good ventilation will shorten drying times. A minimum of 12 days should be allowed when NON-VIT has been used as a mortar for building with new refractory bricks or has been used in deep repairs.

Firing

Raise firing temperature as slowly and evenly as possible, typically at 50°C per hour, until 1000°C is reached. Thereafter, for NON-VIT, the furnace may be heated to its working temperature as usual. For HI-GLAZE the first firing must attain at least 1200°C, thereafter, any temperature up to 1650°C can be used.

Properties

Chemical Analysis of NON-VIT*

*Mainly as oxides

Product Reference No : Q/F Amendment date August 2002

Resistant to temperatures of 1900°C

The claims made in this document are made in good faith and are based on exhaustive tests carried out over a long period.
Polybond Ltd., their agents and their distributors cannot accept any liability for the behaviour of their materials in individual cases.