Unshaped Refractories

Unsaturation, in oils, 10 826 Unsensitization phenomenon, 19 237 Unshaped refractories, 6 491 Unslaked lime, 15 29 Unstabilized liquid sulfur trioxide, 23 517 Unstable angina, 5 109 Unstable flows, 11 761-765 Unstable node, in separating nonideal liquid mixtures, 22 303 Unstable nodes, residue curve maps, 8 790 Unstable reagents, measurement strategies for, 14 621... 

ISO 1927 1984 Prepared unshaped refractory materials (dense and insulating), International Organization for Standardization, Geneva, Switzerland. 

Sand Rammer. The standard rammer for making test-pieces allows a 14 lb (6.25 kg) weight to fall 50 mm on sand contained in a 50 mm diam. mould three blows from the rammer are used in making a standard test-piece. Its use in compaction and workability tests for unshaped refractories is specified in B.S. 1902 Pt. 7.2. 

Prism Test (Air Quench) (PRE/R5 Part 2), test pieces 114 x 64 x 64 mm are cycled between 950°C and a cold air blast for 5 min. followed by a bend test under a load of 0-3MN/m2. The cycle is repeated to rupture, or for 30 cycles. Small Prism Test (B.S. 1902 S.5.11 1986 Method 1902-511. The test pieces are 75 X 50 X 50 mm and subjected to 10 min. cycles between cold and 1000-1200 C, and subjected to an equal stress in each cycle. Testing is to rupture. Water-Quench Test (for unshaped refractories) B.S. 1902 Pt.7.6. The test is a water quench cycle from 1200 C to... 

ISO 1927-1 2012. Monolithic (unshaped) refractory products - Part 1 Introduction and classification. 

Monolithic linings are a relatively recent development and consist of unshaped refractory products [3]. There are two basic types of monolithic linings castable refractory and plastic refractory. 

Initially, when unshaped refractories were first used, the property requirement was kept the same as for shaped refractories, in thatthey mainly replaced linings. Later on, when the use of these refractories became widespread, new standards had to be developed. The first standards on unshaped refractories by the American Society for Testing of Metals (ASTM) were published in 1943 [3]. They were numbered as C 179 and C 181 C 179 covered "drying and firing linear change of plastics and rammings" and C 181 dealt with "workability index of plastic refractories." As noted earlier. World War II saw an increase of about 35% in unshaped refractory production. Specifications were required to obtain the required items from many manufacturers. 

To achieve easier communication and trading within the European community, there was a need to create European standards that was recognized in the mid-1980s. Refractories were also included in these standards. The standard for unshaped refractory products was numbered EN 1402. 

Various terms such as mixes, refractory mixes, ramming mixes, and monolithics are included in the definition of unshaped refractory products. These products are distinguished from bricks, which have a definite shape, are prefired, and are laid. Unshaped refractories are placed in larger sections. For example, a furnace lining consists of unshaped refractories. They have few joints. 

The definition for an unshaped refractory is given in ISO 1927 (5) and EN 1402-1 It is a mixture, which consists of an aggregate and a bond or bonds, prepared ready for use either directly in the condition in which it is supplied or after the addition of a liquid that satisfies the requirements on refractoriness given in ISO R 836. They may contain metallic, organic, or ceramic fiber material. This mixture is either dense or insulating. An insulating mixture is one whose true porosity is not less than 45% when determined in accordance with EN 1094-4, using a test piece prefired to specified conditions. 

There are four types of bond used for making unshaped refractory products ... 

The maximum grain size is the mesh width through which at least 95% by weight of the material can pass. Another definition relevant to an unshaped refractory is the yield by volume, which is the mass of the material as delivered that is necessary to place 1 m [3] of the material, expressed in tons, to the nearest 1%. 

At present, there is an extensive range of unshaped refractory materials. Various subdivisions are discussed in the sections that follow. 

Out of all the unshaped refractory material subdivisions, refractory castables are the most important. These are produced as dense or insulating materials. Formerly, these were made as mixtures of aggregates and calcium aluminate cements. After continuous improvement, they are produced on a very high technical level today. Because of their varieties, they are further classified as follows. 

Apart from the four main subdivisions of unshaped refractory products, a few others are also used. They are enumerated in the following sections. 

Table 20.2 shows the various divisions of unshaped refractories and their installation in tabular form. 

ISO R1927 gives the subdivision of unshaped refractory products according to chemical composition. The various classes of these materials are listed in the following sections. 

Various Divisions of Unshaped Refractories and Their Installation... 

Carbon-containing products are those unshaped refractory products containing more than 1% carbon. 

For a given quality of unshaped refractory material, the method of placement will decide its performance. The following sections detail the different methods of installation as used in various applications. 

The definition of unshaped refractory products mentioned that these products may contain fibers. The addition of various fibers to these products will be discussed further in the following sections. 

Drying and heating up are started once the setting of the unshaped refractory is over. If fhese processes are started after long periods, then the following rules should be observed ... 

R. Krebs, Modem solution of refractory problems with unshaped refractories, in Proceedings of the UNITECR 1999, September 6-9, Berlin, 1999. 

People often talk about modern, intelligent, and innovative refractory products and/or technologies. However, before an evaluation of these words can be made, it seems to be necessary to make a brief review of the unshaped refractory history. Table 1 shows some remarkable highlights of the last 88 years. 

Table 1 Highlights Regarding the Development of Unshaped Refractory Products...

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