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The available invention concerns coated particles of melted alumina, a procedure for the production the same, a Schleifsand, a grinding wheel and a coated abrasive. The EP 161,869 a2 reveals coated abrasive products, which a carrier layer cover sen, on which abrasive grains exhibiting no coat layer are applied, as for example with a Sandpapier. In US 5,143,522 A are geoffenbart alumina zirconium dioxide abrasives, which are improved by additive of reduced titanium dioxide (titanium oxide). The abrasives have a composition, which covers aluminas, Zirkonund titanium dioxide, whereby the titanium dioxide is one of the components of the solid solution of the abrasives. As is described in JIS R6111-1987 for Artificial Abrasives, alumina abrasives, which are manufactured by melts by Baeyer alumina in an electrical furnace, cover white alumina abrasives (WA), pink alumina abrasive (Pa), monocrystalline alumina abrasives (ha) u.dgl. The toughness of the abrasive rises from WA to Pa to ha (ha > Pa > WA), them have however still no suitable sharpening characteristics for tool steel or other hard materials. Attempts were undertaken to coat the surface of the melted alumina with different additives in order to improve their sharpening characteristics. For example the JP-B-29-25620 reveals that a Schleifsand from melted alumina is coated with 0,5 to 2.0% of a Eisenverbindung and heated up on 700 to 950° C, in order to form a thin ferric oxide film on the Schleifsand. The JP-B-40-16594 reveals that a Schleifsand from melted alumina is coated with 0,01 to 1.0% of a chrome connection and heated up on 800 to 1.400°C, in order to form a thin chrome oxide film on the surface of the Schleifsands. The JP-B-44-637 reveals that a Schleifsand from melted alumina is coated with 0,2 to 2.0% of a copper connection and heated up on 900 to 1.250°C, in order to form a thin copper oxide film on the surface of the Schleifsands. The JP-B-44 638 reveals that a Schleifsand from melted alumina is coated with 0,2 to 2.0% of a nickel connection and heated up on 800 to 1.000°C, in order to form a thin nickeloxide film on the surface of the Schleifsands. These coat layers are micro errors of the particles of melted alumina, which arise when grinding the particles of the block, adjust, and improve the sharpening characteristics of the Schleifsands not substantially. Further these coat layers cover physically the surface of the Schleifsands and can be easily peeled. As result of it the sharpening characteristics of the Schleifsands are not improved. The JP-B-39-11196 reveals that a melted alumina is covered with colloidal alumina. Revealed the JP-B-40-14357 that a melted alumina with an organic detention solution is moistened, powders of heat-firm materials, as a Fe2 03 - ZnO MNO mixture, it are applied a TiO2-SiO2-ZnO-Gemisch or TiO2 on the moistened, melted alumina and the melted alumina with the heat-firm powders are heated up, in order the heat-firm powders on the surface of the melted alumina to melt. These coat layers are to improve a moistening of the Schleifsands with a bonding agent with the production of a grinding wheel, so that the toughness of the grinding wheel is improved. The Schleifsand is improved thus not substantially and an improvement of the sharpening characteristics of the Schleifsands is not reached. The subject of the available invention is the creation of coated particles of melted alumina, which can be used as sharpening material with excellent sharpening characteristics or as heat-firm material with excellent thermal shock firmness. The available invention aims in particular outside to improve the connection of the coat layer to the melted alumina by chemical connection of the coat layer and the melted alumina to improve in order to prevent a peeling and a dropping of the coat layer, and the mechanical firmness and tenacity of the alumina particles. In accordance with available invention the coated particles of melted alumina, characterized by are that the particles are coated as a main part with a coat containing aluminum titanate. The alumina particles are characterized according to invention by that the coat consists of aluminum titanate and an alumina connection. RK 407,749 B a further characteristic of the invention consists of that the alumina connection is selected consisting of the group of spinels, in an educated manner made of alumina and an oxide by either Fe, mg, CO, Zn, Mn or Ni. The coat of the alumina particles is titanium oxide-free according to invention; in addition, it can essentially consist of alumina titanate. After a further characteristic of the invention the coat layer a thickness of 10 to M. according to invention _&gt to have the particles a Vickers hardness of; 2,100 kg/mm2. An execution form of the invention consists of that the aluminum titanate of the particle coat - aluminum titanate is. According to invention the particles have a particle size from 3.000 to 20 t M. The invention concerns also a procedure for the production of coated particles of melted alumina, which by it is characterized that it covers the following stages, i.e. that a titanhältige connection on the surface of the particles is applied that the particles are more highly heated up on a temperature of 1.200°C or, in order a coat layer, containing aluminum titanate as a main component, on the surface of the particles to form. The procedure is characterized in accordance with the invention further by that the titanhaltige connection is selected consisting of the group of titanium oxides, titanates, water-soluble titanium connections and titanium alkoxides. After a further execution form of the procedure according to invention titanhaltige connection on the surface of the particles in a quantity of 0,03 to 3.0 parts by weight than TiO2 is applied to 100 parts by weight alumina. Furthermore the procedure is characterized erflndungsgemäß by that the particles are heated up on a temperature between 1.400 to 1.700°C. The invention concerns the moreover one a Schleifsand, which is characterized by that it consists of the coated particles of melted alumina, as they are indicated according to invention above. The invention refers also to a grinding wheel, which exhibits such Schleifsand according to invention, as well as to a coated abrasive, which is characterized according to invention by that it exhibits a such Schleifsand. The particles of melted alumina, used in the available invention, are particles from electrically melted alumina, like under alumina particles in the JIS R6t11-1987 for artificial abrasives as abrasives from brown alumina (A), white alumina (WA), pink alumina (Pa) or monocrystalline alumina (ha) is defined. The particle size, characteristics etc. are not to those in the JIS R6111-1987 limited. In the following the production of the coated particles of melted alumina is described. First a titanhaltige connection on the surface of the particles of melted alumina, like Schleifsand from melted alumina, is applied. The titanhaltige connection can be powders from titanium oxides, like rutile and Anatas, titanates, like iron titanate, magnesium titanate, cobalt titanate, zinc titanate, manganese titanate and nickel titanate, water-soluble titanhaltige connections, like titanium tetrachloride, Metatitanat and titanium acid, titanium alkoxides, like titanium ISO prop. oxide and Titanbutoxid. The quantity of the titanhältigen connection applied on the particle of melted alumina is preferably 0.03 to 3.0 parts by weight TiO= on 100 parts by weight particles of melted alumina. If the quantity of the applied titanhaltigen connection is less than 0.03 parts by weight, to screen end the aluminum titanate is too small, in order to coat the entire surface, 15 the Teitchen from melted alumina. If the quantity of the applied titanhaltigen connection is larger than 3.0 parts by weight, the titanium content is too high, so that aluminum titanate is formed, but not converted TiO2 u.dgl, does not stay, whereby the characteristics of the coat layer are worsened. The applied titanhaltige connection essentially reacts with the alumina under formation of aluminum titanate and education of a coat layer on the surface of the particles of melted alumina. The coat layer on the surface of the particles of melted alumina in accordance with the available invention contains aluminum titanate as at least a main component. The coat layer can contain other alumina connections, which by a reaction between the alumina of the particles of melted alumina and the titanhältigen connection 3 RK 407,749 B to become formed to be able. Preferential alumina connections cover different made of alumina and oxides of bivalent metals, like Fe, mg, CO, Zn, Mn and Ni, formed spinels. It is to be preferred however that the surface coat layer exists made of aluminum titanate. The procedure for applying the titanhaltigen connection on the particles from melted alumina becomes down beschweben. If powders from titanium oxide, titanate cd.dgl, for applying are suitable on the surface of the alumina particles, the mixture of these powders with the alumina particles can be sufficient. If such are sufficient simple mixing and are not applied the powders and from the alumina particles to separate, can the alumina particles first with a FI0ssigkeit, like water, in a quantity from 5 to 20 Gew. - % to be moistened, according to which the powders are applied on the alumina particles. In case of, where a water-soluble or titanium connection soluble in organic solvent is stacked up on the surface of the alumina particles, a solvent is preferably used in such a quantity that the surface of the alumina particles straight is moistened, e.g. to 20 Gew. - %, and the alumina particles are mixed with the solution of the titanium connection. After the titanhaltige connection was applied on the alumina particles, the particles are dried, in order the water or solvent, to remove if available. After drying the solvent is evaporated and titanate, titanium hydroxide cd.dgl, remains on the surfaces of the alumina particles. If the solvent quantity is large, the Solut can walk during the drying procedure, which leads to no homogeneous distribution of the connection on the surface of the alumina particles, or which can agree alumina particles with one another, with the connection between them. In this case, if the quantity of the connection is not large, the aggregate formation is relatively rare, if however the quantity of the connection is large, can the decay of the alumina particle aggregates to a distance of the connection of the alumina particles or to an uneven distribution of the connection on the surfaces of the alumina particles lead. If a relatively large draw central quantity is necessary, used for this reason prefers a Rotationsoder fluidized bed drier, in order to prevent the Agglomerieren or a walking of the Soluts during drying. Drying after applying the connection is accomplished preferably at a temperature from 40 to 90°C, more preferentially at a relatively low temperature in this range during a longer length of time. If the temperature is however 90°C, the water is completely removed after the drying stage and the applied connection disadvantage-detention-proves separated from the alumina particles. The drying time amounts to preferably 10 to 20 hours. Then the dried sample is brought into a crucible, like an alumina crucible, and heated up for example in an electrical furnace to convert around the titanhaltige connection with the alumina. As result the surfaces of the particles of melted alumina with a coat layer from aluminum titanate are beschiohtet. Heating up preferably accomplished at a temperature within the range of 1.200°C up to the fusion point of aluminum titanate, d.i. 1.860°C, more prefers 1,400 to 1.700°C. The aluminum titanate forms at a temperature over for instance for 1.200°C, but a temperature of 1.400°C or more highly is to be preferred, since a lower temperature requires a longer heating time. A temperature of 1.700°C or less is to be preferred, since a temperature can lead near the fusion point from Aluminumtitanat to one verse-internally of the particles. The length of time of heating up on 1.400°C amounts to preferably 30 minutes or more and with heating up on 1.700°C can it as 5 minutes be as short. In this way particles from melted alumina, which are coated with a coat layer from aluminum titanate, are received. In this way coated particles from melted alumina do not have a coat layer from aluminum titanate with a thickness from approximately 10 to 20 M. the titanium connection completely to aluminum titanate were converted and it other titanium connection by Roentgen diffraction determined. No titanium in a depth was found of more than 25 m of the “Feilchenoberfläche. The aluminum titanate, which coats the surfaces of the alumina particles, is a low-temperature aluminum titanate, - Aluminumtitanat. The coated particles according to invention of melted alumina are hard as 4 RKs 407,749 B the appropriate not coated particles of melted alumina and have a Vickers hardness of 2.100 kg/mm2 or more, whereas not coated melted alumina has a Vickers hardness of less than 2,100 kg/mm ". After the heat treatment with 1.200°C or more the coated particles of melted alumina on ambient temperature are gekehlt and gesiebt with a filter or such a thing, in order to receive a pre-determined grain size of the Schleifsands. In this way the Schleifsand with a desired grain size is received. The Schleifsand has generally one as in the JIS R6111-1987 for Artificial Abrasives and in the JIS R6001-1987 for Abrasive Grain Sizes prescribed Komgröße, is however in the available lo invention not limited to these. For example the Schleifsand according to invention has a grain size from 3.000 to 20 i M. The Schleifsand according to invention can be free Schleifsand or using for the production of grinding wheels and coated abrasives like down. A grinding wheel manufactured by forms and binding (or hardnesses) of the Schleifsands with a bonding agent, like a vitreous binder, a metal binder or a resin binder. A Schteifscheibe with a vitreous binder is to be preferred. The binder used for a grinding wheel with vitreous binder is a so-called “Fdtte” and by mixing feldspar, Töpferstein (Toseki), borax, loam and such a thing is manufactured and consists of SiO2, B203, AI2 03, Fe2 03, CaO, MgO, Na2 0, K2 0 etc. a grinding wheel with vitreous binder is manufactured, as a small quantity glue, like Dextrin, is pressed, dried to the above-mentioned binder added, which mixes Schleifsand with the binder, into a form and burned the molded articles. The firing temperature is preferably 950 to 1.150°C. A coated sharpening material is manufactured, as the Schleifsand with an adhesive is bound on a document. The adhesive is, under the criterion distinguished sharpening achievement and water firmness, preferably an adhesive on phenolic resin basis and can in combination with Resorcin or a derivative of it be used, so that the setting conditions are favoured. The underground for the coated abrasive can be for example paper, woven material and not woven material. A polyester fiber fabric is used also in a sanding belt etc. for high power jobs. Woven materials from Synthetikfaser, like nylon fiber, are not used also as underground for sharpening material out not woven material. Under other coated abrasives the JtS (Japanese Industrial standard) gives sharpening cloths (JIS R6251), sandpapers (JIS R6252), water resistant sandpapers (JIS R6253), to Endlosschleifb more nder (JIS R6254), grinding wheels (JIS R6225), Schleifloänder (JIS R6256) and cylindrical sharpening drums (JIS R6257) on, the coated abrasives according to invention are limited however not on that. An important coated abrasive, soft in the JIS is not implemented, does not cover an abrasive from not woven material, which is a flexible sharpening material (sharpening cloth) in form of a not woven material, compound from three components, a Schleifsand, a fiber (e.g. nylon or polyester fiber) and an adhesive. This abrasive from not woven material has a three-dimensional network architecture from arbitrarily oriented and crossed fibers and a large volume of connected areas and a thickness from approximately 2 to 8 mm, so that it exhibits an excellent pliancy and printer getting. EXAMPLES example 1,500 g abrasives from white melted alumina (WA, manufactured of Showa Denko K.K.) with a grain size of #60, one registered into a bowl from SUS304. The grain size of #60 is indicated as 350 to 210 m. 1.25 g Anatas-TiO2 - powder (Ishihara Sangyo K.K., A-100; middle particle size 0.2 p.m, 0.25 Gew. - % TiO2 to 100 Gew. - % alumina) was dispersed in 50 ml distilled water. The received 2.44 weight-per cent dispersion under agitating to the abrasive in the bowl and with this mixed, in order so the TiO2 was added - powders on on the abrasive particles to lay. RKs 407,749 B were then dried the particles during 16 hours in a blower dryer with 60°C, around the remaining water content on 2,3 Gew. - to reduce %. The Schleifmittet coated with powder was transferred into an aluminum crucible and heated up during 7 hours in a Muffelofen up to 1.500°C and kept 10 hours long with 1.500°C, according to which it was left in the furnace cooling. When the temperature in the furnace reached ambient temperature, the abrasive with a filter was gesiebt from 350 to 210 pm, in order agreed raw grain and not converted TiO2 - powders to remove. In this way abrasive particles with a grain size were received from #60. This abrasive had a density of 3,98 g/cm3 and a Vickers hardness of 2.130 kg/mm2 under a reading from 500 G. The abrasive was analyzed by Roentgen diffraction and it was found that at the surface of the abrasive only aluminum titanate had formed. The tenacity of the abrasive measured after one in the JIS R1628-1975 (ball Mill test for Toughness OF Artificial Abrasive) as C-coefficient designated method. About 250 g of a sample are implemented with sets of standard seven, as in the JIS R6001-1987, gesiebt in a Ro-TapRüttler 10 minutes long. At the third filter zurQckgeblLebene abrasives during 10 minutes with the standard seven one gesiebt again. The abrasive remained then at the third filter in a quantity by 100 g is collected as sample which can be tested. This sample becomes in a ball mill in the way husbands described in the JIS R6128-1975. The gemahlene sample is gesiebt 5 minutes long with sets of standard seven and the abrasive and with R (X), stayed at the fourth filter, is weighed designated. The same procedure becomes also using #60 black silicon carbide - abrasives as standard sample, how in the JIS R6128-1975 described, and the weight of the sample with R (S), stayed after grinding in the ball mill at the fourth filter, repeats designated. The C-coefficient is computed according to the following formula: C-coefficient = log [100IR (X)] log [100/R (S)] the tenacity is higher, if the above value of the C-coefficient is lower. The C-coefficient of the abrasive in example 1 was 0,77. Example 2 example 1 was repeated, with the exception that the quantity of TiO2 - powder 5.1 g (1.0 Gew. - Was % TiO2 to 100 Gew% alumina). In this way received abrasive had a density of 3,98 glcm3 and a Vickers hardness of 2,160 kg/mm2 during a reading of 500 G. the C-coefficient was 0,79. The Roentgen diffraction showed that only aluminum titanate on the abrasive surface had formed. Example 3 8, g g Titantetraisopropoxid (manufactured of Wako Junyaku, 0.5 Gew. - % TiO2 to 100 Gew. - % alumina) into a bowl, which contained the same abrasive in the same quantity as in example 1, followed by agitating and then addition and mixing 50 were registered ml to isopropyl alcohol for this, in order to apply hereby the Titantetraisopropoxid after the abrasive surface. The mixture, in which the Titantetraisopropoxid is applied on the abrasive, was warmed up on a hot plate, in order to evaporate under Rehren the entire alcohol. After drying the abrasive was brought in into an alumina crucible and heated up during one time interval by 7 hours in a Muffelofen 1.400°C and held during 2 hours with 1.400°C and left then in the furnace cooling. After the abrasive on ambient temperature was cooled down, the abrasive with 350 to 210 m seven was gesiebt, in order to receive the #60 abrasive, like in example 1. The received abrasive had a density of 3,98 glcm3 and a Vickers hardness of 2.180 kg/mm2 under a reading from 500 G. the C-coefficient was 0,76. 6 RKs 407,749 B I0 the Schleifmitteloberfl che by Roentgen diffraction qualitatively and it was analyzed was determined that only aluminum titanate had formed. Example 4 example 3 was repeated, it became however g, 8 g aqueous titanium tetrachloride solution (manufactured of Showa Titanium K.K. ; Ti-content 15.4 Gew. - %, 0.5 Gew. - % TiO2 to 100 Gew. - % alumina) solved in 50 ml water. In this way received abrasive had a density of 3,98 g/cm3, a Vickers hardness of 2.130 kglmm2 and a C-coefficient of 0,75. The Roentgen diffraction showed that itself only aluminum titanate on the sharpening center [surface had formed. Example example 1 was repeated, it became however 83.1 g 3.02 gew. - % aqueous dispersion of the NiTiOz powder (0.26 Gew. - % TiO2 to 100 Gew. - % alumina) with the Schleifrnittel mixed. The TiNiO3 - Powder was manufactured after the Mitfällmethode. Titanium tetrachloride and nickel tetrachloride became together by neutralization with Natdumhydroxid please. The Kopräzipitat was heated up in presence of sodium chloride after 800°C to the Entsalzen, followed of meals and centrifugation treatment, in order a fine NiTiO3 - or NiO.TiO2 - to powder to receive (middle particle size 0.058 p, m). 83.1 g 3.02 gew. - % aqueous dispersion of the NiTiOz powder (0.26 Gew. - % TiO2 to 100 Gew. - Were mixed % alumina) with the abrasive. In this way received abrasive had a density of 3,99 g/cm3, a Vickers hardness of 2.190 kg/mm2 and a C-coefficient of 0,75. The Schleifmitteloberfl che was analyzed by Roentgen diffraction and it was found qualitative that it consisted of aluminum titanate and nickeloxide alumina spinel. Comparison examples 1 to 2 #60 abrasive particle of white melted alumina (WA) and melted single-crystal alumina (SA), both by Showa Denko K.K made, for their density, hardness and their C-coefficient were examined. Table 1 sample (#60) WA SA density (g/cm2) 3.94 3.95 Vickers hardness under it. Reading from 500 g (kg/mm2) 2,050 2,020 C-coefficient 1.10 0.92 Verqleichsbeispiel 3 this was a control investigation of JP-B-40-16594. 500 g #60 WA-abrasive, like in example 1, became with 5 gew % an aqueous solution of chrome sour anhydride (CrO3) in a quantity of 0,5 Gew. - Mixed % CrO3, in order to lay the Chromtdoxid on on the surface of the abrasive, soft protecting 2 hours on 1.200°C was then heated up, in order to form a coat layer of Chromoxid on the abrasive surface. This abrasive was examined and it was found that it trte a density of 3,96 g/cm3, an Vickers h from 2.070 kg/mm2 and a C-coefficient of 1,05 had. RK 407,749 B, qleichsbeispiel 4 this was a control investigation of JP-B-44-638. #60 WA, like in comparison example 3, became with an aqueous nickel nitrate solution in a quantity of 0,5 Gew. - % Nickelnitrat mixed, dried and 2 hours long on 900°C heated up, in order to receive an abrasive with a nickeloxide layer on its surface. The received abrasive had a density of 3,95 g/cm3, a Vickers hardness of 2.040 kg/mm2 and a C-coefficient of 1,09. Examples 6 to 10 and Verqleichsbeispiele 5 to 8,100 parts by weight of everyone the #60 abrasive from the examples 1 to 5 and the comparison examples 1 to 4 with 13 parts by weight Borsilikatfdtte, 2 parts by weight Dextrin and 2.5 parts by weight water as bonding agents for a vitreous grinding wheel in a mixer were mixed. The boron silicate frit contain 70 Gew. - % SiO2, 7 Gew. - % AI2 03, 18 Gew. - % B2 03, 4 Gew. - % (Na20 + K2 0) and 0.5 Gew. - % (CaO + MgO). The mixture was pressed into the form, whereby the received molded article contained 45% the abrasive. The molded article was dried during 20 hours with 110°C and heated up then hours long on 1.050°C. It was slowly cooled down, whereby the temperature dropped less around 1°C/min or, in particular between 600°C to 500°C. In this way a vitreous grinding wheel with a degree of hardness K, like in the JIS R6210, was implemented received. All grinding wheels had an outside diameter of 200 mm, an inside diameter of 50.8 mm and a thickness of 19 mm. Examples 11 to 15 and, clleichsbeispiele 9 to 12 the sharpening characteristics of the vitreous grinding wheels from the examples 6 to 10 and the comparison examples 5 to 8 were examined under the following conditions. Machine: Okamoto Oberflächenschleifer PSG-52DX (3.7 KW) Schleifart: Plunge-cut grinding manual parting piece of work: SUJ-2 (HRc 60), 100mm Lx50 mm of Hx 10mmT disk peripheral speed: 2,000 m/min face plate circulation: 20 m/min Einstechgeschwindigkeit: ACRE 20 per/course total depth adjustment: 5 mm sharpening width: 10 mm of Ausfeuern: 1 sharpening oil: Noritake coolly K-82B (water-soluble sharpening oil) straightening conditions: Monolithic diamond dressing tool, parting: ACRE 20 m/Gang upward gradient: 0,2 mm/disk revolution Ausfeuern: no the results of the sharpening achievements, maximum capacity (value with departure of the no-load operation achievement (0.4 KW)) and surface roughness of the pieces of work are shown in table 2. RK 407,749 B table 2 sample BP. 11 BP. 12 BP. 13 BP. 14 BP. V-BP. 9 V-BP. V-BP. 11 V-BP. 12 Schleiß means BP. 1 BP. 2 BP. 3 BP. 4 BP. V-BP. 1 V-BP. 2 V-BP. 3 V-BP. 4 Schleifgeschwindig kt. (mm3/mm3) 62 68 61 36 39 33 max. Leistg. - admission (kWtcm) 1.6,1.6,1.5,1.7,1.5,2.1,1.9,1.9,2.0 Oberfl. - is rauhheit (FLmRz) 9 8 8 9 11 9 11 as in table 2 shown the grinding wheels, had the grinding wheels, on use of the abrasives according to invention in the grinding wheels, importantly higher grinding speeds than the grinding wheels with commercial WA-abrasives (about 2 times), the grinding wheels with SASchleifmittel (about 1.7 times), with abrasive, coated with chromic acid from the comparison example 3, (about 1.5 mA!) and the grinding wheels with abrasives coated with nickel from Vergieichsbeispiel 4 (about 1.8 times). Although the grinding speeds from the examples 11 to 13 in the comparison with the Vergleichsbe play {g to 12 are excellent, the maximum capacities from the examples are smaller than those excellent from the comparison examples and the value of the Oberfiächenrauhheit regarding the comparison examples. Example 16 an abrasive was manufactured after the same procedures as in example 1, except that the output abrasive a Schleifrnittel from decomposition alumina, containing 0.30 Gew. - Was % TiO2 (Showa Denko K.K., SA). The received abrasive had a density of 3,98 g/cm a Vickers hardness of 2.210 kgtmm2 and a C-coefficient of 0,69. At the time of execution of a Roentgen diffraction only Aluminumtitanat on the abrasive surface was found. Using this abrasive a grinding wheel was manufactured in the same way as in the examples 6 to 10 and geprOft on sharpening achievement in the kind as in example 11 to 15. As result the grinding speed was 78 mm3/mm3, the maximum capacity 1.5 kW/cm and the surface roughness 8 i March. Example 17 it was manufactured, abrasives in the same procedure as in example 1, except that Bayer's alumina with 0,7 Gew. - % titanium oxide mixed, melted and in a LJ htbogenofen was solidified and rubbed and gesiebt, whereby #60 became to receive abrasives. After TiO2 - Powder on the surface of this Sch was applied] eifmittels, the particles 5 hours long on 1.400°C was heated up. In this way received Schleifrnittel had a density of 3,97 g/cm a VickersH trte from 2.150 kg/mm2 and a C-coefficient of 0,70. Roentgen diffraction resulted in that only Aluminumtitanat on the abrasive surface had formed. Ver.qleichsbeispiel 13,500 g #60 Sch (eifmittef from brown melted alumina (Showa Denko K.K., A-40) RK 407,749 B became with a dispersion from 13 g Anatas-l-iO2 - powder (Ishihara Sangyc K.K., A-100, middle particle size 0.2 l m) in 100 ml destUliertem water mixed and under agitating mixes, in order the TiO2 - powders on the surface of the abrasive to lay on. After laying on the abrasive was dried 20 hours long with 60°C in a blower dryer, around 2,8 Gew. - To lose % water. The abrasive was transferred into an alumina crucible and heated up in a Muffelofen in 6 hours 1.400°C and kept 3 hours long with 1.400°C. In this way received abrasive had a density of 3,98 g/cm3, a Vickers hardness of 2020 kg/mm2 under a reading from 500 g and a C-coefficient of 1,10. These values did not differ from those, which had been received before the treatment, d.i. a density of 3,98 g/cm3, a hardness from 2.010 kg/mm2 and a C-coefficient from 1,10. The Roentgen diffraction showed that the abrasive had a coating of predominating titanium oxide with a smaller quantity aluminum titanate. Reason, why the abrasive, after titanium oxide on its surface had been even laid on and it had been heated up, did not have improved characteristics, lies, assumed, therein that the surface of the abrasive was coated with a glasslike phase, itself additionally to aluminum titanate from a considerable quantity of impurities due to a considerable quantity of impurities, as titanium oxide, silicagel formed and from the inside of the abrasive escaped ferric oxide. In accordance with the vodiegenden invention contain the particle of melted alumina a chemical connection between the coat layer and the alumina particle, coated with a coat from Aluminumtitanat, so that the coat layer is not peeled. Therefore, with use this particle becomes as sharpening material, which improves sharpening achievement in comparison with conventional abrasives.