Sci. Semicond. Process. 41, 497–507 ... and vanadium oxide (V 2 O 5) addition on the structural, optical and electrical properties of corundum (α-Al 2 O 3). Sci Rep 13, 16100 (2023 ...

The three main technological steps for fabricating ceramic corundum abrasives based on sol–gel process are as follows: synthesis of precursors, particle shaping, and sintering. This study introduces the mechanism of seeds and sintering additives, the machinability of special shape abrasive particles, the particle shaping …

Here the authors report the ultrafast synthesis of corundum nanoparticles via the resistive hotspot triggered phase transformation in electric heating process.

Corundum is easily synthesized, and many Corundum abrasives are synthetic. Synthetic gems are also easily created by adding traces of certain color producing elements to the Corundum solution, and letting the solution solidify into a boule, or synthetic, unprocessed "mineral" with a particular shape. This process is called the Verneuil process.

The phase transformation synthesis of α-Al 2 O 3 NPs is realized with a low-energy input of ~4.77 kJ g –1 or $0.027 kg –1 in electrical energy cost, which is at least 20× less energy ...

Ruby is a gemstone and a variety of the mineral corundum (Al2O3) that is distinguished by its red color, which is caused by trace amounts of chromium in the crystal structure. Ruby is a very hard and durable gemstone, with a hardness of 9 on the Mohs scale, and is often used in jewelry such as rings, necklaces, and bracelets. Ruby is also …

1. The furnace is charged with the material. 2. The roof is lowered and closed. 3. Electrodes are lowered onto the material to form the arc between the material and the electrodes. 4. Arc is struck at a lower voltage which is thereafter increased to speed up the melting process.

Abstract. In its nanoparticulate form, corundum (α-Al 2 O 3) could lead to several applications. However, its production into nanoparticles (NPs) is greatly …

There are two specific mechanisms of corundum formation based on location within the furnace. 4.1.1. Internal Corundum Growth Internal corundum formation occurs due to reduction process of refractory components by aluminum metal and alloying elements. Below the liquid metal line refractory surface is the main area for internal …

Thermodynamic calculations indicate that this transformation is driven by the shift in stability from boehmite to α-Al 2 O 3 caused by milling impacts on the surface energy. Structural water in boehmite plays a crucial role in generating and stabilizing α-Al 2 O 3 NPs. Corundum (α-Al 2 O 3) in high-surface-area nanoparticle (NP) form ( 1, 2 ...

Brown corundum dust is a solid waste produced during the preparation of brown corundum with bauxite as the raw material. The dust has a relatively high...

White corundum is made of alumina powder, which is smelted at a high temperature above 2000 ℃ in an electric arc furnace. It is crushed and shaped, iron is removed by magnetic separation, and sieved into various particle sizes. It has a dense texture, high hardness, and a sharp grain shape. Angular hardness is slightly higher than brown corundum, …

Abstract. The energy band structure of corundum is investigated theoretically using the semiempirical Mulliken-Rüdenberg method. A crystal potential is constructed basing on …

Aluminum oxide, with the chemical formula Al2O3 A l 2 O 3, is an amphoteric oxide and is commonly referred to as alumina. Corundum (α-aluminum oxide), emery, sapphire, amethyst, topaz, as well as many other names are reflecting its widespread occurrence in nature and industry. Corundum is the most common naturally …

First, the precursor of ceramic corundum abrasive was prepared with a solid content of 60-70%. Prior to the laser cutting step, the coating of the precursor was achieved via scraping, roller ...

First Online: 04 November 2022. pp 21–23. Cite this chapter. Download book PDF. Download book EPUB. Bozena Arnold. 127 Accesses. Abstract. We already know that …

The corundum structures of In2O3:Sn (ITO) nanoparticles were synthesized by hydrothermal processing of InCl3 and SnCl4·5H2O precursor at low temperature of 250 °C and 40 bar pressure for 3 h. The precursor was precipitated in a white gel of InOOH. After drying at 150 °C in air, it was crystallized in orthorhombic structure. InOOH powder …

Physical Structure. J.P. Lafemina, in Handbook of Surface Science, 1996 4.3.5 Corundum surfaces. The corundum oxides, led by corundum itself, α-Al 2 O 3, are perhaps the most technologically important class of oxide materials.Some are excellent catalysts, while α-alumina is one of the most widely used substrates for the growth of thin metal, …

Scientific analysis, using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), identified the material as a mixture of predominant angular grains of corundum (aluminum oxide, Al2O3) with jagged edges and a few other minerals such as quartz, rutile, feldspar, apatite, ilmenite, augite, biotite, and …

Refractory raw material plate corundum, zirconium corundum introduction and electric fused corundum production process: Introduction of plate corundum: Is a pure, no additives such as MgO, B2O3 and other sintered corundum shrinkage thoroughly, with coarse crystal, well-developed α-Al2O3 crystal structure.

Corundum smelting is carried out in a short-furnace reduction electric furnace, which provides heat by electrical energy to melt the raw materials and allow the reduction reaction to proceed. The reduction reaction in the smelting process is carried out after the alumina is melted, and the reducing agent is solid carbon.

Corundum. There are a few forms of aluminum oxide, and corundum being the most common. The structure of corundum can be viewed as a hexagonal close packed array of oxygen atoms with 2 / 3 of the octahedral sites occupied by Al 3 + ions. Thus, the Al 3 + ions are bonded to 6 oxygen in a distorted octahedron. Each such octahedron share …

The molecular weight of the corundum is 101.96, the true density is 3.99 g/cm 3, the melting point is 2043–2109 °C, and the heat of fusion is 109.2 kJ/mol. Melting is accompanied by a 23.5% increase in volume. The nature of the Al–O chemical bond determines the structural features of liquid corundum.

Corundum was the first gem mineral to be synthesized in the lab by a process known today as flame fusion. A somewhat more difficult process, flux growth, is also used to …

Corundum is a form of aluminum oxide (Al₂O₃) typically containing traces of iron, titanium, vanadium, and chromium. Corundum powder is a granular, white, odorless powder that is chemically inert. Corundum is a hard mineral with a high density and is the index mineral for a hardness of nine on the Mohs Hardness Scale. Typical Applications.

In the conduction process of corundum type materials, the possible mobile charge carriers are electrons, holes and oxygen vacancies . The formation of …

Aluminum oxide is an ionic compound. It is made up of aluminum which is a metal, and oxygen, a nonmetal. Whenever a compound contains both a metal and a nonmetal, it is considered an ionic ...

7. Operations. This is a list of all of the operations involved in sending and receiving packets, across both hardware and software. 7.1. Packet transmission. linux: The Linux kernel calls mqnic_start_xmit() (via ndo_start_xmit()) with an sk_buff for transmission. mqnic_start_xmit() ( mqnic_tx.c ): The driver determines the destination transmit ...

In this process, limestone is used as a slag–forming agent to react with impurity oxides ... Corundum is a refractory raw material with Al 2 O 3 as the ... and the types and contents of elements in the micro-area of the sample were analyzed by X-ray energy dispersive spectrometer (EDS, Phoenix EDS Microanalysis system, EDAX, Inc., …

This process involves taking the necessary oxide components for gem corundum (e.g., Al 2 O 3, Fe 2 O 3, TiO 2, Cr 2 O 3) in powdered form and melting them together in a hot container that is just barely over the crystallizing temperature. A rod with a small corundum seed crystal is lowered into the molten material and then very slowly removed.

The process of electron transfer results in the absorption of energy owing to the overlap of d orbitals on these metals. Thus, an intervalence charge transfer between Ti 3+ and Fe 3+ was the underlying dominant mechanism postulated for the blue colouration of the sapphires [ 13 ] that produced the metastable Fe 2+ /Ti 4+ configuration [ 17 ].

Brown corundum dust is a key carrier of gallium, which is created during the pro-duction of brown corundum using electric arc furnace high-temperature smelting tech-nology [30]. The recovery of valuable components from brown corundum dust can im-prove resource utilization and generate revenues for the brown corundum industry. How-

The morphology of the product obtained by the calcination-leaching process of BAD is shown in Fig. 9. The product is mainly composed of α-alumina and magnesia alumina spinel. The corundum phase presents different morphological characteristics, such as lamellar or rod-like, and cross-links with the magnesia-aluminum spinel.

The ingredients were weighed according to the designed A-series formula, and the samples were prepared according to the sample preparation process as shown in Fig. 3, after step (b) ball milling (the ratio of the material to the balls was 1:3), step (c) granulation (10–16 wt% of water was added to the mixed powder by spray-drying method), aging (24–48 h), and …