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                                                                                                                                                                    1.    Introduction:
1.2.        N )anotechnology(Introduction   The Nano-technology phrase originating from two words consist of the Greeknumerical prefix nano referring to a billionth and the technology word 1-3. As an outcome, Nano-technology or Nano-scaled technology is commonly
considered to be at a size under 100 nm (a Nano-meter is 10-9 m) 1-2.  
2.      Refractories: 2.1. Introduction:  
According to the ASTM C 71 , the refractories are a “non-metallic
materials having those physical and chemical properties that lead to them
applicable for structures or as components of systems that are exposed to
environments above 1000 °F (538°C) 11, 16. Also, some references mentioned that refractories are in-organic non-metallic material
which can withstand high temperature without changing in their chemical or physical
properties while remaining in contact with molten slag, metal and gases 11-13, 16-20. As well as, according to the operating situation, they should to have high thermal shock resistant, be chemically inert, and  have definedranges of thermal conductivity and thermal expansion coefficient 11- 21, 22. It is clear that refractories have an important role in glassmaking, metallurgical, and ceramic industries, where they are generated into a variety of shapes to line the interiors of
furnaces or kilns or other devices for processing the
materials at high temperatures 23-25. Some of the technological and scientific inventions and progresses would not have been possible withoutrefractory materials. Producing 1Kg of any metal without utilize of refractory is almost quite impracticable 26-29.The history of using refractory materials dates back to since mankind start to develop
metallurgical process. The firstrefractor raw material was clay. Up to the nineteenth century, refractory products were made of natural ores, such asmagnesite, dolomite stones and was at the end of the eighteenth century and
beginning of nineteenth century that the basis of modern metal beneficiation,
the development of Portland cement and of modern glass processes started to
inflict higher requirements to the refractory industry 30-33. The main materials used in the producing ofrefractories are based to Fig.1 34-36. In recent years, with the changing trends in
steelmaking, the high performing shaped refractories are on an increasing demand. The higher campaign lives and the mutability of the
newer steelmaking operations are decided by the accessibility and performance of such shaped
refractories with superiorhigh-temperature mechanical strength, erosion and corrosion
resistance the selection of refractories to be utilized is often according to the conditions dominating in the application zone 36-40.   2.2.       
Classification : Generally,refractories
are divided based on chemical composition, manufacturing method, and physical shape or based on their applications (Fig.2) 11-20, 40-55. 2.2.1. Based on chemical composition: a) Acidic refractories: These types of refractories are used in region that slag and atmosphere are acidic. They have high resistance to acids but corroded by alkalis. The main raw materials belong to the RO2 category, such as SiO2, ZrO2 and etc. b) Neutral refractories: These categories of refractories are used in area that atmosphere and slags are chemically resistant to both acids andbases.
The major raw materials related to,
but not confined to, R2O3 category. The general examples of thesematerials are Al2O3, Cr2O3 and
carbon(C). c) Basic refractories: These categories of refractories are used in area that atmosphere and slags are basic; these categories high resistance to alkaline materials but corroded by acids. Themajor raw materials related to the RO category to which MgO is a very general example. Also, (Mg.Ca (CO3)2 and (MgO-Cr2O3)
are in these categories.   2.2.2. according to producing method: a) Dry press. b) Fused cast. c) Handmolded. d) Formed (normal, fired or chemically bonded). e) Un-formed (monolithic- plastic, ramming and gunningmass, castables).   2.2.3. according to physical
shape: a) Formed: These types have determined shapes and size. These types divided into standard shapes and special shapes. The first type has size that is confirmed by mostrefractory
producer and is generally suitable to furnaces or kilns of the same types. The second type specifically made for special furnaces or kilns. b) Un-formed: These categories are without clear format and are only given shapeupon application. Un-formed are known as monolithic refractories. The common examples castables are, plasticmasses, gunning masses, ramming masses, fettling mix, mortars etc.   Monolithic Refractories:
Monolithic refractoryphrase is the name
usually given to all un-shaped refractory products, the word “monolithic” extracted from the word monolith which means ‘big stone’56-58. Monolithic refractories are specific batches or blends of dry granular or cohesive
plastic materials utilized to form nearly joint
free linings. Monolithic refractory are un-shaped products which are installed as some form of suspension that finally harden to create a solid shape. Most
monolithicformulations are made of three constituent such as: large refractory particulates (an aggregate), fine filler materials(which fill the inter particle voids) and a binder phase (that gels the particulates together in the
green state) Fig 359-65. Monolithic refractories show a great range of
mineral compositions and vary greatly in their physical andchemical
properties. Some of them have low melting point (low
refractoriness) whiles others approach high purity brick
compositions in their ability to tolerate severe environments. Monolithic refractories are replacing theconventional
type fired refractories at a much faster rate in many applications
including those of industrial furnaces53-55, 66-68. These refractories are used to advantage compare to brick construction in different type
of furnaces. Their use enhanced fast installation. Utilize of monolithic refractories often delete difficult brick laying tasks, whichmay be accompanied with looseness in construction. Protect of furnaces is very importance
because substantial repairs can be made with a minimum loss of time
69-74. Sometimes, monolithic refractories linings of the same
composition as firebrick provide better insulation, lower diffusion and enhanced spalling resistance to the effects of repetitive thermal
shock. Other major benefits of monolithic refractory linings are as follows 75-80: ü Removingjoints
which is an inherent weakness. ü Easier and faster application.  ü
Better properties than pressed (sintered or tempered) bricks. ü Simpler transportation and handling. ü Better volume
stability. ü Possibility to install in hot standby state. ü
Higher mechanical resistance to vibration and impact. ü confirming shrinkage and expansion to the application. Different
methods are used in the placement of monolithic
refractories such as ramming casting, spraying, gunning, sand slinging and etc. Heat setting monolithic refractories have a very low cold strength values and rely on relatively high temperatures to progress a ceramic bond 81-83. Furnaces wall having the
usual temperature drop across its thickness, the temperature in the cooler part is generally not enough to progress aceramic bond. However with the use of a proper insulating material as backup, the
temperature of the lining can behigh
enough to progress a ceramic bond throughout its entire thickness. In order to the
installation and curing, monolithic refractories need an intently controlled dry-out
program. This led to the filler, binder and aggregate to firegenerating a high strength material 84-86.   3.1. Types of
monolithic refractories Usually the monolithic refractories are divided according
to Fig.4 56-60, 65-88 a) Castable refractories  Materials with
hydraulic setting in nature are name of Castables. These refractories are
containing cement binder (commonly aluminate cement), which creates hydraulic
setting properties when blended with water. By heat-up temperature, the
material and binder either transforms or volatilizes simplifying the generation of a ceramic bond. The most common binder used in castables is high alumina cement. Other binders are
consisting of hydratable alumina and colloidal silica. These materials are
installed by casting and are also known as refractory concretes. Insulating
castables are specialized monolithic refractories that are used on the cold surfaces of
applications. These monolithic castables are composed of lightweight aggregate
aggregates such as vermiculite, bubble alumina, perlite
and expanded clay. The main function of castables is to create thermal insulation. Also, they are generally had low density and low thermal conductivity. The
castables are classified according
to following 48-58: ü Conventional Castable. ü Low Cement Castables (LCC). ü Ultra Low Cement Castable (ULCC). ü
No Cement Castable (NCC). ü Light Weight Castables. ü Self-FlowCastables (SFC). ü Insulating Castable.   b) Plastic refractories Plastic refractories are used to form refractory
monolithic linings in different types of furnaces. These refractories are suitable for making quick, economical emergency repairs and they are easily rammed to any shape or contour. Plastic refractories are consisting
of refractory aggregates and adhesive clays which are prepared in stiff plastic condition at the proper consistency for use
without more preparation. During utilization, the blocks are tasked into pieces
and are rammed or casted into place with pneumatic
rammer.  These refractories can also be casted into place with a mallet.
These refractories suitable for many important applications due to the high
melting point (high refractoriness), the range ofcompositions,
and the ease with which plastic refractories are rammed into place make them. Also, they
have often highly spalling resistant. Plastic refractories can consist of all the, clay-graphite, fireclay, high alumina, high aluminagraphite
and chrome types adapted for many various operating
situations. Specific gunning types are also accessible. These are in granulated shape and are produced at the proper consistency, ready to use. Some examples of plastic refractories are 65-69, 76-80: ü Heat setting super duty fireclay plastic, ü Super duty heat setting plastics with graphite,
ü Plastics in the 50 

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