In recent years, the use of nanotechnology (nanoparticles, nanomaterials and nano-additives) has attracted the attention of academics, engineers and scientists from all over the world. scientific fields such as chemistry, medicine, materials, agriculture, electricity, etc. The use of nanotechnology has also become widespread in refractory products (mainly used by various industries such as steel, foundry, cement, glass, etc.). Therefore, many researchers have evaluated the effect of using different types and contents of nanomaterials (oxides and non-oxides) on the properties of shaped (bricks) and unshaped (monolithic) refractory products and obtained results very interesting. One of the most consumable refractory products in various industries is monolithic refractories, which have been widely used due to their great advantages over other refractory products (bricks). Therefore, in this article, recent advancements in monolithic refractories through nanotechnology are presented. This article can be considered as a comprehensive reference and guide for researchers, students and artisans to easily access experimental research results on the impact of nanotechnology on monolithic refractories. Say no to plagiarism. Get a tailor-made essay on "Why violent video games should not be banned"?Get the original essayNanotechnology (Introduction)The two-word phrase nanotechnology consists of the Greek numerical prefix nano referring to one billionth and the word technology [1- 3]. As a result, nanotechnology or nanoscale technology is generally considered to be less than 100 nm in size (a nanometer is 10-9 m) [1-2]. According to ASTM C 71, refractories are “nonmetallic materials having physical and chemical properties that make them applicable to structures or as components of systems exposed to environments above 1,000 °F (538 °C) [11, 16] . Furthermore, some of the references mention that refractories are non-metallic inorganic materials that can withstand high temperatures without changing their chemical or physical properties while remaining in contact with molten slag, metal and gases [11-13, 16-20]. depending on the operating situation, they must have high resistance to thermal shock, be chemically inert and have defined ranges of thermal conductivity and thermal expansion coefficient[11-21,22]. It is clear that refractories play an important role in the glassmaking, metallurgy and ceramics industries, where they are generated in various forms to line the interior of furnaces or other devices for processing materials to be processed. high temperature [23-25]. . Certain inventions and technological and scientific progress would not have been possible without refractory materials. Producing 1 kg of any metal without using refractory is almost impossible [26-29]. The history of the use of refractory materials dates back to when humanity began to develop metallurgical processes. The first raw material for the refractor was clay. Until the 19th century, refractory products were made from natural ores, such as magnesite, dolomite stones and clay. It was in the late 18th and early 19th centuries that the basis of modern metal beneficiation, the development of Portland cement, and modern glassmaking processes began to place higher demands on the industryrefractory [30-33]. The main materials used in the production of refractories are based on Figure 1 [34-36]. In recent years, with changing trends in steel manufacturing, high-performance shaped refractories are in increasing demand. Higher campaign lives and mutability of new steelmaking operations are determined by the accessibility and performance of these shaped refractories with high temperature mechanical strength, erosion and corrosion resistance superior. The selection of refractories to be used is often a function of the prevailing conditions in the area of ​​application [36-40]. Generally, refractories are divided based on chemical composition, manufacturing method and physical form or based on their applications (Fig.2) [11-20, 40 -55].Based on chemical composition: Acid Refractories: These types of refractories are used in regions where the slag and atmosphere are acidic. They have high resistance to acids but are corroded by alkalis. The main raw materials belong to RO2 category, such as SiO2, ZrO2, etc. Neutral Refractories: These categories of refractories are used in areas where the atmosphere and slag are chemically resistant to acids and bases. The main raw materials related to, but not limited to, the R2O3 category. General examples of these materials are Al2O3, Cr2O3 and carbon (C). Basic Refractories: These categories of refractories are used in areas where the atmosphere and slag are basic; These grades have high resistance to alkaline but acid-corroded materials. The main raw materials related to the RO category of which MgO is a very general example. Additionally, (Mg.Ca(CO3)2 and (MgO-Cr2O3) are in these categories. According to production method: Dry press. Cast iron. Hand cast. Formed (normal, drawn or chemically bonded). Unformed. (monolithic-plastic, ramming and shooting mass, moldable elements).Depending on the physical form:Formed: These types have determined shapes and sizes. These types are divided into standard and special shapes. size confirmed by most refractory producers and is generally suitable for kilns or kilns of the same type. The second type is specially designed for special kilns or kilns: these categories do not have a clear format and are. Unformed are known only as monolithic refractories Common examples of moldable products are plastic masses, firing masses, ramming masses, roughing mixes, mortars, etc. monolithic is the name usually given to all unshaped refractories. products, the word “monolithic” is taken from the word monolith which means “large stone”[56-58]. Monolithic refractories are specific batches or blends of dry granular or cohesive plastic materials used to form nearly seamless coatings. Monolithic refractories are unshaped products that are installed as a slurry which ultimately hardens to create a solid form. Most monolithic formulations consist of three constituents such as: large refractory particles (an aggregate), fine filler materials (which fill the inter-particle voids) and a binder phase (which gels the particles together in the state Green). Fig 3[59-65]. Monolithic refractories exhibit a wide range of mineral compositions and vary considerably in their physical and chemical properties. Some of them have a low melting point (low refractoriness), while others come closehigh purity brick compositions in their ability to tolerate harsh environments. Monolithic refractories are replacing conventional type refractories at a much faster rate in many applications, including those in industrial furnaces [53-55, 66-68]. These refractories are used advantageously over brick construction in different types of kilns. Their use has improved the speed of installation. The use of monolithic refractories often eliminates the difficult tasks of laying bricks, which can be accompanied by slack in construction. Furnace protection is very important because major repairs can be carried out with minimal loss of time [69-74]. Sometimes monolithic refractory linings of the same composition as refractory bricks provide better insulation, lower diffusion and better resistance to spalling from the effects of repetitive thermal shock. The other major advantages of monolithic refractory linings are as follows [75-80]: ü Removal of joints which constitute an inherent weakness. ü Easier and faster application. ü Better properties than pressed (sintered or tempered) bricks. ü Simpler transport and handling. ü Better volume stability. üPossibility of installation in hot standby state. ü Superior mechanical resistance to vibrations and shocks. ü confirm the removal and expansion of the application. Different methods are used for placement of monolithic refractories such as ramming casting, spray casting, gunning, sand slinging, etc. Monolithic thermosetting refractories have very low cold strength values ​​and depend on relatively high temperatures. advance a ceramic bond [81-83]. Since the kiln wall has the usual temperature drop across its entire thickness, the temperature in the coldest part is generally not sufficient to advance a ceramic bond. However, with the use of a suitable insulating material as a backing, the temperature of the coating can be raised high enough to progress. a ceramic binder over its entire thickness. For installation and curing, monolithic refractories require a tightly controlled drying program. This led to the filler, binder and aggregate igniting, generating high strength material [84-86]. Usually, monolithic refractories are divided according to Figure 4 [56-60, 65-88] Hydraulically setting materials in nature are named Castables. These refractories contain a cement binder (usually aluminate cement), which creates hydraulic setting properties when mixed with water. Due to the heating temperature, the material and binder transform or volatilize, thereby simplifying the generation of a ceramic bond. The most commonly used binder in concrete is cement with a high alumina content. Other binders consist of hydratable alumina and colloidal silica. These materials are installed by casting and are also called refractory concretes. Insulating concretes are specialized monolithic refractories used on cold surfaces in applications. These monolithic concretes are composed of lightweight aggregates such as vermiculite, bubble alumina, perlite and expanded clay. The main function of concrete is to create thermal insulation. In addition, they generally have low density and low thermal conductivity. Concretes are classified according to the following elements [48-58]: ü Conventional casting. ü Low cement content concretes (LCC). ü Castable in very low content cement (ULCC). ü No pourable cement (NCC). ü Light castables. ü Castablesautomatic flow (SFC). ü Pourable insulation. Plastic refractories are used to form monolithic refractory linings in different types of furnaces. These refractories are suitable for making quick and economical emergency repairs and are easily pressed into any shape or contour. Plastic refractories consist of refractory aggregates and adhesive clays which are prepared in a rigid plastic state and with the appropriate consistency for use without additional preparation. During use, the blocks are cut into pieces and are rammed or driven into place with a pneumatic rammer. These refractories can also be put in place with a mallet. These refractories are suitable for many important applications due to their high melting point (high refractoriness), range of compositions and the ease with which plastic refractories are set up. Additionally, they are often very resistant to chipping. Plastic refractories can be made of all types of clay-graphite, fire clay, high alumina, high alumina graphite and chromium suitable for many different operating situations. Specific types of shots are also available. These are in pellet form and are produced with the appropriate consistency, ready to use. Some examples of refractory plastics are [65-69, 76-80]: ü Super strong thermosetting refractory plastics, ü Super strong thermosetting plastics with graphite, ü 50% alumina class plastics, ü 60% alumina class plastics % thermosetting, ü High alumina plastics with air intake in 80% alumina class, ü High alumina plastics bonded to phosphate with alumina content ranging from 70% to 90%, ü Plastics with chrome alumina base bonded to phosphate, ü And phosphate-based plastics bonded to silicon carbide. Ramming mixtures composed essentially of crushed refractory aggregates, with a semi-plastic bonding matrix structure. These refractory materials resemble plastic refractories but are much harder. They need some sort of shape to keep them going once formed. Particle sizes are carefully graded and the final product is usually made dry and then mixed with a little water just before use. Other ramming products are rendered in a wet state and are ready for use immediately after opening. Ramming mixtures are placed with a pneumatic rammer in layers of 25 mm to 40 mm. Steel fabrication, burner blocks, ports and similar applications used with high purity mullite grain based ramming mixtures. Pounding mixes contain 80 weights. % alumina content have good resistance to shrinkage and thermal spalling at high temperatures. Some ramming mixtures, such as high stabilized alumina air setting, have good resistance to thermal spalling at high temperatures and volume stability up to their temperature limit. In addition, phosphate-bonded alumina-chromium ramming mixtures generally have very high high temperature strength and very good resistance to acid and neutral slag consisting of coal ash slag. Alumina-graphite ramming mixtures contain a blend of grain inhibitors and high alumina slags which give them good resistance to acidic and slightly basic slags. In the steel industry, dry ramming mixtures based on high purity MgO and a sintering aid are useful. Magnesite mixtures of exceptional purity and stability are used primarily.