text:
Patent US4680130 - Preparation of finely divided isotropic ferrite powders having the spinel ... - Google PatentsSearch Images Play Gmail Drive Calendar Translate Books More »Advanced Patent Search | Web History | Sign inAdvanced Patent SearchPatentsA process for the preparation of ferrite powders which have a particle fineness which can be set to a defined value, of the general composition M(II).sub.x Fe(II).sub.1-x Fe(III).sub.2 O.sub.4 and M(II).sub.x Fe(III).sub.3-x O.sub.4.5-0.5x where M is Mg, Mn, Co, Ni, Cu and/or Zn and x is from 0 to 1,...http://www.google.sh/patents/US4680130?utm_source=gb-gplus-sharePatent US4680130 - Preparation of finely divided isotropic ferrite powders having the spinel structurePublication numberUS4680130 APublication typeGrantApplication number06/780,458Publication date14 Jul 1987Filing date26 Sep 1985Priority date28 Sep 1984Also published asEP0176919A2EP0176919A3EP0176919B1InventorsHartmut HibstOriginal AssigneeBasf AktiengesellschaftU.S. Classification252/62.6G9B/5.267106/459423/594.3252/62.64423/594.1252/62.62International ClassificationH01F1/44C08K3/24C09C1/22G11B5/706C09D5/23H01F1/117C01G49/00C04B35/26H01F1/36C01G51/00C01G53/00C09C1/24Cooperative ClassificationC09C1/24C01P2004/64C04B35/26C01P2006/12C01G49/0018C01G51/00C01G49/0072C08K3/24B82Y30/00C01P2004/62C09C1/22C01G53/00C01G49/0036C01P2002/32C01G49/0063C01P2006/42H01F1/117G11B5/70678H01F1/445European ClassificationB82Y 30/00C01G 49/08H01F 1/117C01G 49/00C4C01G 49/00C10C01G 53/00C04B 35/26C01G 49/00CC08K 3/24H01F 1/44PC01G 49/00C12C09C 1/24C09C 1/22C01G 51/00G11B 5/706C6DReferencesPatent Citations (7)Referenced by (15)External LinksUSPTOUSPTO AssignmentEspacenetPreparation of finely divided isotropic ferrite powders having the spinel structureUS 4680130 AAbstract A process for the preparation of ferrite powders which have a particle fineness which can be set to a defined value, of the general composition
I claim: 1. A process for the preparation of a finely divided ferrite powder which has the spinel structure, is of the formula M(II).sub.x Fe(III).sub.1-x Fe(III).sub.2 O.sub.4 where M is Mg, Mn, Co, Ni, Cu and/or Zn and x is from 0 to 1, and has an essentially isotropic particle shape, wherein an oxygen-containing gas is passed into a coprecipitate prepared from an aqueous alkali metal hydroxide solution, an M(II) salt solution, an iron(II) salt solution and an iron(III) salt solution, the ratio of the iron(III) ions to the sum of the M(II) and Fe(II) ions in the coprecipitate being smaller than that in the resulting ferrite powder of the composition M.sub.x Fe.sub.3-x O.sub.4.
2. A process for the preparation of a finely divided ferrite powder which has the spinel structure, is of the formula M(II).sub.x Fe(III).sub.3-x O.sub.4.5-0.5x, where M is Mg, Mn, Co, Ni, Cu and/or Zn and x is from 0 to 1, and has an essentially isotropic particle shape, wherein the ferrite powder repared as described in claim 1 and of the formula M.sub.x Fe.sub.3-x O.sub.4 is oxidized in the dry state at 100 C. with an oxygen-containing gas.
4. A process as claimed in claim 2, wherein the oxygen-containing gas used for the oxidation in the dry state at 100
Fe.sub.3 O.sub.4 pigments or Zn.sub.x Fe.sub.3-x O.sub.4.5-0.5x pigments having a high BET specific surface area which can be set to a defined value are required for dyeing plastics, or other organic binders for the production of colored coatings, in transparent black or orange to yellow hues. If the BET specific surface area of the pigment is too low, the resulting colorations are not transparent but high-hiding. If it is too high, one of the effects is that the dispersibility of the pigments is adversely affected. Furthermore, Fe.sub.3 O.sub.4 pigments and Zn.sub.x Fe.sub.3-x O.sub.4 pigments having a high BET specific surface area which can be set to a defined value are desirable for the preparation of magnetic liquids. If the BET specific surface area of the magnetic particles is too low, the particles agglomerate and flocculate, the magnetic liquid losing its superparamagnetic property. On the other hand, an extremely high specific surface area of the pigment has an adverse effect on its saturation magnetization and therefore also on the saturation magnetization of the magnetic liquid, since it is known that the non-magnetic part of the pigment surface increases as the pigment becomes more finely divided. Similarly, γ-Fe.sub.2 O.sub.3 pigments and Zn.sub.x Fe.sub.3-x O.sub.4.5-0.5x pigments which can be overdyed and have a high, but not extremely high, BET specific surface area which can be set to a defined value are required for the preparation of colored magnetic liquids and inks. Moreover, very dense, magnetically soft polycrystalline MnZn or NiZn ferrite ceramics are required for the preparation of magnetic heads. The head-dependent noise and the permeability of such magnetic heads, eg. hot-pressed magnetic heads, increase as the fineness of the structure decreases. It has also been found that, when the ferrite ceramic is processed to magnetic heads having narrow recording tracks, the mechanical stability of the said ceramic improves as the particle size decreases. For the preparation of the stated fine-particled ferrite ceramics, correspondingly finely divided MnZn or NiZn ferrite pigments having a particle size which can be set to a defined value are therefore required. On the other hand, starting ferrite pigments which are too finely divided cannot be homogeneously compacted during sintering and therefore result in a ferrite ceramic which has an undesirably high porosity.
Ferrite powders which have the spinel structure and are of the general formula M(II).sub.x Fe(II).sub.1-x Fe(III).sub.2 O.sub.4, where M is Mg, Mn, Co, Ni, Cu and/or Zn, and 0≦x ≦1, can be prepared by a wet-chemical route, by two different methods.
In the neutralization process, a coprecipitate having a pH of 11-13 is used as the starting material. It is prepared by combining an aqueous alkali metal hydroxide solution, an M(II) salt solution and an Fe(III) salt solution (where x is 1, the addition of Fe(II) salt solution is dispensed with). The coprecipitate is then heated without passing in an oxidizing gas. Frequently, heating of the coprecipitate is even carried out under a non-oxidizing protective gas, eg. nitrogen or argon. This gives an extremely finely divided ferrite powder which has the composition M.sub.x Fe.sub.3-x O.sub.4 [=M(II).sub.x Fe(II).sub.1-x Fe(III).sub.2 O.sub.4 ], where 0≦x ≦1, and an isotropic particle shape. In the neutralization process, the ratio of the iron(III) ions to the sum of the M(II) and iron(II) ions in the coprecipitate is the same as that in the resulting ferrite of the composition M.sub.x Fe.sub.3-x O.sub.4. Thus, the Fe(III)/(M(II) +Fe((II)) ratio remains constant during the reaction, and the ferrite formation reaction is therefore not a redox reaction. The ferrite powders obtained are extremely finely divided and, depending on the reaction conditions, possess particle diameters of about 50-200 Å; the BET specific surface areas of the pigments are from 70 to 300 m.sup.2 /g. Because they are extremely finely divided, these pigments obtained in colloidal form are difficult to isolate by a filtration process. Moreover, washing the filter cake is very tedious. In addition, extremely hard masses are formed when the precipitated powders are dried. It is impossible to prepare readily dispersible ferrite powders from these hard masses by pulverizing them. Furthermore, the extremely finely divided magnetic pigments prepared by the neutralization process generally have a lower saturation magnetization than coarse-particled pigments of the same composition, which is a disadvantage. This is a consequence of the large non-magnetic part of the pigment surface. Moreover, after they have been subjected to oxidation in the dry state with an oxygen-containing gas at, for example, 300 M.sub.x Fe.sub.3-x O.sub.4.5-0.5x, the extremely finely divided ferrite pigments M.sub.x Fe.sub.3-x O.sub.4 prepared by the neutralization process exhibit sintering of the extremely fine particles which is detectable from a sharp decrease in the BET specific surface area. This sintering results in a further deterioration in the dispersibility. Another consequence of the extremely finely divided nature of the ferrite powders prepared in this manner is that in general they cannot be compressed homogeneously during cold-pressing or hot-pressing, a ferrite ceramic which has an undesirably high porosity being obtained.
In the second process, the oxidation process, the starting material used is a coprecipitate prepared by combining an aqueous alkali metal hydroxide solution, an M(II) salt solution and an Fe(II) salt solution. The coprecipitate is heated, and oxidized with an oxidizing gas, in general air, until a ferrite powder which has the composition position M.sub.x Fe.sub.3-x O.sub.4 [=M(II).sub.x Fe(III).sub.2 O.sub.4 ], where 0≦x≦1, and an isotropic particle $hape is obtained. In the oxidation process, an Fe(III)-free coprecipitate is used as a starting material, and some of the Fe(II) of the coprecipitate is oxidized to the Fe(III) in the resulting ferrite powder. During this procedure, the initial pH of the coprecipitate would be shifted to smaller values, ie. into the acidic range, if alkali metal hydroxide solution were not added constantly during the reaction. It has been disclosed (U.S. Pat. No. 3,822,210) that the fineness of the particles of the ferrite powders obtained by the oxidation process can be varied within a limited range by suitable choice of the reaction parameters, such as pH and reaction emperature. Moreover, under certain reaction conditions, the M(II) concentration x has an effect on the resulting fineness of the pigment particles. However, we have found that, using the oxidation process, it is extremely difficult to prepare M(II)-containing magnetite powders or M(II) ferrites having a particle diameter of less than 0.15 μm and a BET specific surface area greater than 12 m.sup.2 /g. When technical-grade iron(II) chloride solutions are used, particular problems are encountered as regards obtaining a very finely divided pigment. A particular disadvantage of the inadequate pigment particle fineness achievable by the oxidation process is that the resulting colored pigments possess poor transparency. Moreover, the achievable fineness of the pigment particles is insufficient to produce a stable magnetic liquid or ink. Moreover, in order to produce special highly permeable and low-noise ferrite ceramics, it is desirable to start from ferrite powders which are fairly finely divided.
It is an object of the present invention to provide a preparation process which makes it possible to obtain, in an economical manner, isotropic M.sub.x Fe.sub.3-x O.sub.4 ferrites [=M(II).sub.x Fe(II).sub.1-x Fe(III).sub.2 O.sub.4 ], where M is Mg, Mn, Co, Ni, Cu and/or Zn and 0≦x≦1, which have a particle fineness which can be set to a defined value and which is larger than the extremely small particle size obtainable by the neutralization process and smaller than the comparatively coarse particle size obtainable by the oxidation process. It is a further object of the present invention to provide a preparation process which makes it possible to obtain, in an economical manner, isotropic M.sub.x Fe.sub.3-x O.sub.4.5-0.5x ferrites [=M(II).sub.x Fe(III).sub.3-x O.sub.4.5-0.5x ] where M is Mg, Mn, Co, Ni, Cu and/or Zn and 0≦x≦1, which have a particle fineness which can be set to a defined value and essentially corresponds to that of the abovementioned M.sub.x Fe.sub.3-x O.sub.4 pigments.
We have found that this object is achieved, and that finely divided ferrite powders of the general formula M.sub.x Fe.sub.3-x O.sub.4 [=M(II).sub.x Fe(II) .sub.1-x Fe(III).sub.2 O.sub.4 ], where M is Mg, Mn, Co, Ni, Cu and/or Zn and 0≦x≦1, having an essentially isotropic particle shape and the desired fine particle size, can be prepared if an oxygen-containing gas is passed into a coprecipitate prepared from an aqueous alkali metal hydroxide solution, an M(II) salt solution, an iron(II) salt solution and an iron(III) salt solution, the ratio of the iron(III) ions to the sum of the M(II) and Fe(II) ions in the initial coprecipitate being smaller than that in the resulting ferrite powder of the composition M.sub.x Fe.sub.3-x O.sub.4.
We have also found that finely divided ferrite powders of the general formula M.sub.x Fe.sub.3-x O.sub.4.5-0.5x [=M(II).sub.x Fe(III).sub.3-x O.sub.4.5-0.5x ], where M is Mg, Mn, Co, Ni, Cu and/or Zn and 0≦x≦1, which essentially have an isotropic particle shape and the desired fine particle size, can be obtained if ferrite powders which have the composition M.sub.x Fe.sub.3-x O.sub.4, contain the same ions M, have the same limits for x, and are prepared by passing an oxygen-containing gas into a coprecipitate produced from an aqueous alkali metal hydroxide solution, an M(II) salt solution, an iron(II) salt solution and an iron(III) salt solution, the ratio of the iron(III) ions to the sum of the M(II) and Fe(II) ions in the initial coprecipitate being smaller than that in the resulting ferrite powder of the composition M.sub.x Fe.sub.3-x O.sub.4, are oxidized with an oxygen-containing gas at from 100
The novel process for the preparation of ferrite powders of the general formula M.sub.x Fe.sub.3-x O.sub.4 differs from neutralization proceses in that, in contrast to the latter, the Fe(III)/(M(II)+Fe(II)) ratio in the starting coprecipitate does not correspond to that in the resulting ferrite powder. In the novel process, the said ratio in the starting coprecipitate is always smaller than that in the resulting ferrite powder of the composition M.sub.x Fe.sub.3-x O.sub.4, where 0≦x≦1. Furthermore, the process according to the invention is associated with the chemical conversion of gaseous oxygen via a redox reaction, whereas the neutralization process is carried out under a protective gas and hence in the absence of oxidizing gases. Since the novel process gives pigments which are coarser-particled than those obtained by the neutralization process, no filtration and washing problems arise in the novel process, as are encountered in the neutralization process.
The novel process for the preparation of ferrite powders of the general formula M.sub.x Fe.sub.3-x O.sub.4 differs from the oxidation process in that the latter starts from a coprecipitate containing an alkali metal hydroxide, an M(II) salt and an Fe(II) salt but no Fe(III) salt, whereas the novel process is based on a coprecipitate containing an iron(III) salt. In carrying out the novel process, we have found, surprisingly, that the particle size of the resulting ferrite powder having the composition M.sub.x Fe.sub.3-x O.sub.4, where M is Mg, Mn, Co, Ni, Cu and/or Zn and 0≦x≦1, and hence also the particle size of the ferrite obtained by oxidation in the dry state, having the composition M.sub.x Fe.sub.3-x O.sub.4.5-0.5x and containing the same ions M and having the same limits for x, decreases as the amount of Fe(III) in the coprecipitate increases. As the amount of Fe(III) in the coprecipitate increases, the particle diameter decreases from about 0.15 μm to about 0.02 μm. The corresponding pigments have BET specific surface areas of from about 12 to about 100 m.sup.2 / g. Thus, using the process according to the invention, it is possible to prepare substantially more finely divided pigments than can be prepared by the oxidation process. On the other hand, the novel process permits the preparation of pigments which are coarser-particled than those obtainable by the neutralization process.
For a given M/Fe ratio, the isotropic pigments prepared according to the invention, of the composition M.sub.x Fe.sub.3-x O.sub.4 and M.sub.x Fe.sub.3-x O.sub.4.5-0.5x , where M is Mg, Mn, Co, Ni, Cu and/or Zn and 0≦x≦1, surprisingly possess substantially better dispersibility, better ferrimagnetic properties, in particular a fairly high saturation magnetization, and better compressibility during cold-pressing or hot-pressing than the known isotropic ferrites obtained by the neutralization process. The pigments prepared according to the invention differ from the known ferrite powders obtained by the oxidation process, having more finely divided particles and a narrower particle size distribution. These improvements in the ferrite powder are also very clearly noticeable when it is used as a transparent colored pigment, for the preparation of magnetic liquids and inks and for the preparation of highly permeable magnetically soft ferrite ceramics, and is also noticeable when the pigment is used for the preparation of plastic-bound ferrites, ie. plastoferrites.
EXAMPLE 1 In a 5 liter stirred vessel, a solution of 27.26 g of ZnCl.sub.2 in 2 liters of H.sub.2 O was mixed with 1,057 ml of a technical-grade iron(II) chloride solution having a concentration of 33.59 g/100 ml of FeCl.sub.2, while stirring and passing in 200 liters/hour of pure nitrogen. Aqueous NaO H solution and H.sub.2 O were added to the resulting solution until the pH was 7.5 and the total volume was.4 liters. Thereafter, the coprecipitate was heated to 90 nitrogen was discontinued and, instead, 200 liters/hour of air were passed into the coprecipitate. The pH of the reaction mixture was kept constant at the set value of 7.5 by continuously adding a 2.5 molar sodium hydroxide solution. Air was passed in until the Fe(II) content of the reaction mixture remained constant. The reaction time was about 5 hours. The dispersion was cooled, and the resulting ferrite powder was then filtered off, washed and dried.
The following pigment properties were measured on the resulting isotropic zinc-containing iron oxide having the composition Zn.sub.0.2 Fe.sub.2.8 O.sub.4 : H.sub.c =11 kA/m, Mr/ρ=17nTm.sup.3 /g, M.sub.s/ ρ=99 ntm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=12 m.sup.2 /g.
The resulting zinc-containing magnetite having the composition stated above was then oxidized with 200 liters/hour of air for 1 hour at 300 in a rotating quartz flask. The following pigment properties were measured on the resulting isotropic zinc-containing iron(III) oxide having the composition Zn.sub.0.2 Fe.sub.2.8 O.sub.4.4 : H.sub.c =9 kA/m, M.sub.r/ ρ=23 ntm.sup.3 /g, M.sub.s/ ρ=90 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=11.5 m.sup.2 /g.
EXAMPLE 2 In a 5 liter stirred vessel, a solution of 27.26 g of ZnCl.sub.2 was mixed with 553.8 ml of a technical-grade iron(II) chloride solution having a concentration of 41.20 g/100 ml of FeCl.sub.2 and with 283.7 ml of a technical-grade iron(III) chloride solution having a concentration of 57.18 g/100 ml of FeCl.sub.3, while stirring and passing in 200 liters/hour of pure nitrogen. The resulting solution was further treated as described in Example 1. The reaction time was about 4 hours.
The following pigment properties were measured on the resulting isotropic zinc-containing magnetite having the composition Zn.sub.0.2 Fe.sub.2.8 O.sub.4 : H.sub.c =9 kA/m, M.sub.r/ ρ=28 nTm.sup.3 /g, M.sub.s/ ρ=106 nTm surface area)=20.3 m.sup.2 /g.
The zinc-containing iron(IlI) oxide of the composition Zn.sub.0.2 Fe.sub.2.8 O.sub.4.4 obtained after the subsequent oxidation in the dry state carried out as described in Example 1 had the following pigment properties: H.sub.c =8 kA/m, M.sub.r /ρ=24 nTm.sup.3 /g, M.sub.s/ ρ=81 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=19.2 m.sup.2 /g.
EXAMPLE 3 In a 5 liter stirred vessel, a solution of 27.26 g of ZnCl.sub.2 was mixed with 430.7 ml of a technical-grade iron(II) chloride solution having a concentration of 41.20 g/100 ml of FeCl.sub.2 and with 397.2 ml of a technical-grade iron(III) chloride solution having a concentration of 57.18 g/100 ml of FeCl.sub.3, while stirring and passing in 200 liters/hour of pure nitrogen. The resulting solution was further treated as described in Example 1. The reaction time was about 2 hours.
The following pigment properties were measured on the resulting isotropic zinc-containing magnetite having the composition Zn.sub.0.2 Fe.sub.2.8 O.sub.4 : H.sub.c =1 kA/m, M.sub.r/ /ρ=5 nTm.sup.3 /g, M.sub.s/ ρ=78 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific) surface area)=56.7 m.sup.2 /g.
The zinc-containing iron(III) oxide of the composition Zn.sub.0.2 Fe.sub.2.8 O.sub.4.4 obtained after the subsequent oxidation in the dry state carried out as described in Example 1 had the following pigment properties: H.sub.c =0 kA/m, M.sub.r /ρ=6 nTm.sup.3 /g, M.sub.s /ρ=66 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=53.8 m.sup.2 /g.
EXAMPLE 4 In a 5 liter stirred vessel, a solution of 27.26 g of ZnCl.sub.2 was mixed with 252.80 ml of a technical-grade iron(II) chloride solution having a concentration of 40.12 g/100 ml of FeCl.sub.2 and with 567.38 ml of a technical-grade iron(III) chloride solution having a concentration of 57.18 g/100 ml of FeCl.sub.3, while stirring and passing in 200 liters/hour of pure nitrogen. Aqueous NaOH solution and H.sub.2 O were added to the resulting solution until the pH was 7.5 and the total volume was 4 liters. Thereafter, the coprecipitate was heated to 90 After a reaction time of 1 hour, the dispersion was cooled and the ferrite product obtained was filtered off, washed and dried.
The following pigment properties were measured on the resulting isotropic zinc-containing magnetite having the composition Zn.sub.0.2 Fe.sub.2.8 O.sub.4 : H.sub.c =1 kA/m, M.sub.r/ ρ3 nTm.sup.3 /g, M.sub.s/ ρ=69 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=77.5 m.sup.2 /g.
The zinc-containing iron(III) oxide of the composition Zn.sub.0.2 Fe.sub.2.8 O.sub.4.4 obtained after the subsequent oxidation in the dry state carried out as described in Example 1 had the following pigment properties: H.sub.c =0 kA/m, M.sub.r/ ρ=2 nTm.sup.3 /g, M.sub.r/ ρ=56 n .sup.Tm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=72.9 m.sup.2 /g.
EXAMPLE 5 In a 5 liter stirred vessel, a solution of 54.52 g of ZnCl.sub.2 was mixed with 842.12 ml of a technical-grade iron(II) chloride solution having a concentration of 39.14 g/100 ml of FeCl.sub.2, while stirring and passing in 200 liters/hour of pure nitrogen. The resulting solution was further treated as described in Example 1. The reaction time was about 5 hours.
The following pigment properties were measured on the resulting isotropic zinc-containing magnetite having the composition Zn.sub.0.4 Fe.sub.2.6 O.sub.4 : H.sub.c =10 kA/m, M.sub.r/ 13 nTm.sup.3 /g, M.sub.s/ ρ=110 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=12.1 m2/g.
The zinc-containing iron(III) oxide of the composition Zn.sub.0.4 Fe.sub.2.6 O.sub.4.3 obtained after the subsequent oxidation in the dry state carried out as described in Example 1 had the following pigment properties: H.sub.c =6 kA/m, M.sub.r/ ρ=16 nTm.sup.3 /g, M.sub.s/ ρ=84 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=10.8 m.sup.2 /g.
EXAMPLE 6 In a 5 liter stirred vessel, a solution of 54.52 g of ZnCl.sub.2 was mixed with 647.8 ml of a technical-grade iron(II) chloride solution having a concentration of 39.14 g/100 ml of FeCl.sub.2 and with 170.21 ml of a technical-grade iron(III) chloride solution having a concentration of 57.18 g/100 ml of FeCl.sub.3, while stirring and passing in 200 liters/hour of pure nitrogen. The resulting solution was further treated as described in Example 1. The reaction time was about 4 hours.
The following pigment properties were measured on the resulting isotropic zinc-containing magnetite having the composition Zn.sub.0.4 Fe.sub.2.6 O.sub.4 : H.sub.c =8 kA/m, M.sub.r/ ρ=21 nTm.sup.3 /g, M.sub.s/ ρ=99 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=28.9 m.sup.2 /g.
The zinc-containing iron(III) oxide of the composition Zn.sub.0.4 Fe.sub.2.6 O.sub.4.3 obtained after the subsequent oxidation in the dry state carried out as described in Example 1 had the following pigment properties: H.sub.c =6 kA/m, M.sub.r/ ρ20 nTm.sup.3 /g, M.sub.s/ ρ=82 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=26.8 m.sup.2 /g.
EXAMPLE 7 In a 5 liter stirred vessel, a solution of 54.52 g of ZnCl.sub.2 was mixed with 518.22 ml of a technical-grade iron(II) chloride solution having a concentration of 39.14 g/100 ml of FeCl.sub.2 and with 283.69 ml of a technical-grade iron(III) chloride solution having a concentration of 57.18 g/100 ml of FeCl.sub.3, while stirring and passing in 200 liters/hour of pure nitrogen. The resulting solution was further treated as described in Example 1. The reaction time was about 3 hours.
The following pigment properties were measured on the resulting isotropic zinc-containing magnetite having the composition Zn.sub.0.4 Fe.sub.2.6 O.sub.4 : H.sub.c =3 kA/m, M.sub.r/ ρ=10 nTm.sup.3 /g, M.sub.s/ ρ=85 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=49.1 m.sup.2 /g.
The zinc-containing iron(III) oxide o the composition Zn.sub.0.4 Fe.sub.2.6 O.sub.4.3 obtained after the subsequent oxidation in the dry state carried out as described in Example 1 had the following pigment properties: H.sub.c =0 kA/m, M.sub.r/ ρ=6 nTm.sup.3 /g, M.sub.s/ ρ66 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=46.0 m.sup.2 /g.
EXAMPLE 8 In a 5 liter stirred vessel, a solution of 54.52 g of ZnCl.sub.2 was mixed with 194.33 ml of a technical-grade iron(II) chloride solution having a concentration of 39.14 g/100 ml of FeCl.sub.2 and with 567.37 ml of a technical-grade iron(III) chloride solution having a concentration of 57.18 g/100 ml of FeCl.sub.3, while stirring and passing in 200 liters/hour of pure nitrogen. The resulting solution was further treated as described in Example 4.
The following pigment properties were measured on the resulting isotropic zinc-containing magnetite having the composition Zn.sub.0.4 Fe.sub.2.6 O.sub.4 : H.sub.c =0 kA/m, M.sub.r/ ρ=1 nTM.sup.3 /g, M.sub.s/ ρ63 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=80.8 m.sup.2 /g.
The zinc-containing iron(III) oxide of the composition Zn.sub.0.4 Fe.sub.2.6 O.sub.4.3 obtained after the subsequent oxidation in the dry state carried out as described in Example 1 had the following pigment properties: H.sub.c =0 kA/m, M.sub.r/ ρ= nTm.sup.3 /g, M.sub.s/ ρ=54 nTm.sup.3 /g, S.sub.N.sbsb.2 (BET specific surface area)=73.4 m.sup.2 /g.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS382221010 Aug 19722 Jul 1974Iwase K,JaFine spinel-type ferrite particles featuring high dispersibility and the process of manufacture of sameUS428974528 Apr 198015 Sep 1981Basf Wyandotte CorporationPigments stable at high temperaturesUS429229425 Jan 198029 Sep 1981Basf Wyandotte CorporationYellow pigments stable at high temperaturesUS433624219 Nov 197922 Jun 1982Dornier System Gmbh.Hard ferrite powder and process for the preparation thereofUS442525016 Aug 198210 Jan 1984Basf AktiengesellschaftPreparation of finely divided ferrite powdersUS447354223 May 198325 Sep 1984Celanese CorporationProduction of microcrystalline ferrimagnetic spinelsUS448640114 Mar 19834 Dec 1984Celanese CorporationProduction of fine ferrimagnetic spinelsReferenced byCiting PatentFiling datePublication dateApplicantTitleUS482653723 Oct 19872 May 1989Basf AktiengesellschaftLamellar pigments of the general formula Mn.sub.X -Al.sub.Y Fe.sub.2-(X+Y) O.sub.3US50733591 Mar 199017 Dec 1991Selenia Industrie Elettroniche Associate S.P.A.Process for manufacturing ceramic magnetic materialUS508071823 Feb 198914 Jan 1992Engelhard CorporationInorganic pigments of the empirical formula A.sub.x B.sub.y C.sub.zUS515476922 Jan 199113 Oct 1992Bayer AktiengesellschaftProcess for production of black manganese/iron oxide pigmentUS516400518 Mar 199217 Nov 1992Bayer AktiengesellschaftBlack manganese/iron oxide pigment a process for its production and its useUS51640074 Dec 198917 Nov 1992Bayer AgBlack pigment, process for its preparation and its useUS526984118 Jun 199214 Dec 1993Bayer AktiengesellschaftTemperature-resistant black pigment, a process for its production and its useUS530230621 Jun 199312 Apr 1994Sony CorporationProcess for preparing polycrystalline ferrite materials and composites containing themUS533642110 Aug 19939 Aug 1994Toda Kogyo Corp.Spinel-type spherical, black iron oxide particles and process for the producing the sameUS566287929 Apr 19962 Sep 1997Northrop Grumman CorporationMethod for preparation of ferrite powders at room temperatureUS709141217 Feb 200415 Aug 2006Nanoset, LlcMagnetically shielded assemblyUS716230225 Feb 20049 Jan 2007Nanoset LlcMagnetically shielded assemblyUS747928821 Jun 200420 Jan 2009Henkel Kommanditgesellschaft Auf AktienNanoparticulate preparationUS765158015 Dec 200826 Jan 2010Henkel Kommanditgesellschaft Auf Aktien (Henkel Kgaa)Nanoparticulate preparationUS801693519 Jun 200613 Sep 2011Ferrinov Inc.Anti-corrosion pigments coming from dust of an electric arc furnace and containing sacrificial calciumRotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google

value: Google Patents is a search engine from Google that indexes patents and patent applications.


text:
Cyber Security Agency: Researchers find “severe” flaw in WordPress plugin with 1 million installs
The vulnerability stems from a "severe" SQL injection bug in NextGEN Gallery, a WordPress plugin with more than 1 million installations. Until the flaw was recently fixed, NextGEN Gallery allowed input from untrusted visitors to be included in WordPress-prepared SQL queries. Under certain conditions, attackers can exploit the weakness to pipe powerful commands to a Web server's backend database.
"This is quite a critical issue," Slavco Mihajloski, a researcher with Web security firm Sucuri, wrote in a blog post published Monday. "If you're using a vulnerable version of this plugin, update as soon as possible."
from Researchers find “severe” flaw in WordPress plugin with 1 million installs

type: global

value: Blogger is an American online content management system (CMS) which enables multi-user blogs with time-stamped entries. Pyra Labs developed it before being acquired by Google in 2003.


text:
Double up frames | DIY for the HOME | Pinterest | Frames and DIY
Lovely Little Snippets: Double-up your frames! {DIY} I love this look. Diy Frame, Chunky Frame, Lovely, Picture Frames, Snippets, Craft Ideas, Diy Projects
LOVE this frame! spray paint two frames white then choc brown, then white again and distress. Then just double up the two frames.
Glue two frames together to make one big chunky frame! via @ Lovely Little Snippets Cheryl Sousan | Tidymom.net from lovelylittlesnippets.blogspot.com
Glue two frames together to make one big chunky frame! via @ Lovely Little Snippets. Great idea.
Brooke Dieterich
Great idea! Glue two frames together to make one big chunky frame! via @ Lovely Little Snippets
Lovely Little Snippets: Double-up your frames! {DIY} Frame stacking for a chunkier frame
Lovely Little Snippets: Double-up your frames! {DIY} I love this look.
Lovely Little Snippets: Search results for distress frames
Lovely Little Snippets-double up picture frames
Love these... DIY - Double Frames
Diy Frame, Monogram Picture Frame, Diy Picture Frame, Pallet Gift, Christmas Gift
Loving this cute DIY Picture Frame! Would make great Christmas gifts! gonna do this weekend with my mom here!
Loving this cute DIY Picture Frame I want to do something like this on the family picture shelf
DIY Picture Frame by @Shanti Leeuwen Yell-2-Chic.com - Would make great Christmas gifts!
Loving this cute DIY Picture Frame! Would make great Christmas gifts! "I" for Ingles :)
Photo frame on wood board with letter
such a cute personalized diy frame
Jessica Walker-Fruitman
Home Decor- Crafts/DIY
paper garlands :: lets make this for KCH's birthdays instead of using paper streamers in the doors! she could even help by doing the sewing. craft camp idea
from Etsy Lovely Paper Garlands
#DIY lovely paper garlands my DIY for tomorrow!
Paper Garlands, Paper Craft, Paper Punch, Craft Ideas, Diy Paper
CONNECTED WITH STITCHING FROM A SEWING MACHINE! #DIY lovely paper garlands
#DIY lovely paper garlands - nice idea to use the sewing machine
#DIY lovely paper garlands - such a fresh looking, simple idea
#DIY lovely paper garlands but do it with photos for a dorm
#DIY lovely paper garlands.
#DIY paper garlands
Diy Frame, Shadowbox, Cheap Frames, Shadow Box, Cute Apartment Decoration, Frame Shelves, Display Shelves
I love this! DIY display shelves using cheap frames... SO cute and easy! www.shanty-2-chic.com
simple DIY frame shelves! Lgreat way to reuse old frames or to dress up cheap frames
Stuff I Dream of Making
Gigi's GoneShopping
Gallery walls/wall decor
Lovely framing compositions - how helpful!
Diy Ideas, Mirror Diy, Beautiful Mess, Art Piece, Starburst Mirror, Diy Mirror, Craft Ideas, Diy Projects, Bedroom
STARBURST MIRROR DIY - Starburst mirrors are so chic in metallics and I'm really loving gold accents lately. I wanted to create something for our bedroom that replaced an old art piece that wasn't really working and that also added more light to a dark corner in that space. I can definitely make this with those scrap pieces of wood.
Starburst Mirror DIY from A Beautiful Mess. Love it. So many ways to personalize it.
Starburst Mirror DIY [the amazing Miss Rachel Denbow for A Beautiful Mess]
IMG_1650a a beautiful mess starburst mirror DIY modern
Starburst Mirror DIY - Smile and Wave/A Beautiful Mess
Starburst Mirror DIY // a beautiful mess
Starburst Mirror DIY {Mirror}
Glue two frames together for a chunkier look - LOVE this idea!
Photo Gallery Wall, Craft, Wood, Stenciled Photo, Photo Frames, Diy Wall Art, Easy Diy
EASY DIY Photo Frames. Debating between wood and canvas... Also, may use for a different use other than a frame.
EASY DIY Photo Frames. Gonna try these for sure. Debating between wood and canvas... love her blog though--Ive done a few of her projects. more info about Photo Frames read here : http://cardboardphotoframes.net/
EASY DIY Photo Frames. Gonna try these for sure. I have some empty wood frames i could do this with!
EASY DIY Photo Frames. Gonna try these for sure. Debating between wood and canvas... love her blog though
EASY DIY Photo Frames. You can use wood or canvas.
Learn more at lovelylittlesnippets.blogspot.com.au
Beautiful simple DIY wreath
Holiday, Idea, Craft, Twig Wreath, Christmas, Diy, Wreaths
Alisha Blokker
Learn more at the-inspiration-station.com
{note to self: I should do this type thing with the holiday cards I've saved from from closest loved ones and then display them on the appropriate holiday}
Christmas Cards, Vintage Christmas Card Craft, Vintage Santa, Old Christmas Card Craft, Vintage Card, Christmas Picture Frame
<3 Embellished Christmas picture frame with mini bottle brush tree & bow with a Vintage Santa postcard inside.
Great idea!! Need to find those vintage cards I have and do this!!
find cute vintage christmas cards and put in cute frame
Vintage Santa Print in distressed frame - Love it!
Vintage card in a frame - Cute Christmas project
Great way to repurpose christmas cards
frame those awesome Christmas cards
What a cute Christmas craft!
Frames wrapped in maps.
diy stool - Website full of tutorials, remakes, and crafts. Scroll to the bottom.
Like this for me :-) DIY footstool from reclaimed wood. site also has tutorials for pallet wood projects crafts
Beyond The Picket Fence: Stool Tute Tute! Yes! One of these for our lil people to use in the bathroom!
Beyond The Picket Fence: Stool Tute Tute! - could use for someone too short to use the sink or to do the dishes!!!!
Beyond The Picket Fence: Stool Tute Tute! - longer legs and it would be a great side table too
Chalkboard framed with beautiful red frame.
Chalkboards, Craft, Frames, Chalk Board, Framed Chalkboard, Chalkboard Idea
chalkboard idea with an amazing frame! Perfect for the kitchen or craft room. picture frame chalkboard. I may need to do this for my "command center"! picture frame chalkboard.. for the kitchen to add menu, messaes, etc..
picture frame chalkboard I NEED THIS!! So gorgeous! LOVE COLOR RED!
{stitch your trip onto a map then frame it}

value: Pinterest is an American image sharing and social media service designed to enable saving and discovery of information (specifically "ideas") on the internet using images and, on a smaller scale, animated GIFs and videos, in the form of pinboards. The site was created by Ben Silbermann, Paul Sciarra, and Evan Sharp and had over 478 million global monthly active users as of March 2021.


text:
Deal Shopping Mama: Amazon: FREE 30 Day Prime Trial !(Includes Two Day shipping,$10 Amazon GiftCard, Free Movies & Shows + More) (Reg. $79.00)
Amazon: FREE 30 Day Prime Trial !(Includes Two Day shipping,$10 Amazon GiftCard, Free Movies & Shows + More) (Reg. $79.00)
Amazon is offering a Free 30 Day Prime Trial – Enjoy all the same benefits as paid members. As part of this limited time, exclusive offer, at the conclusion of your Free Trial, if you purchase an annual membership, you’ll receive a $10.00 Amazon.com Gift Card. Go here
When they renew your membership, they use the card you gave us at sign-up. If they can’t successfully charge this card, they’ll use another payment method. Your initial sign-up authorizes us to use the preferred or other available payment methods. To update your preferred card, go to Manage Your Prime Membership HERE .
Note: At the end of a free trial period, you’ll be automatically upgraded to a paid annual membership for $79. You can opt out at any time during the free trial period. For more information, go to Cancel Your Amazon Prime Membership HERE .