Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
160 words
A process for preparing metallic powders based on iron and suitable for magnetic recording, starting from acicular particles of an iron compound selected from the class consisting of α-Fe 2 O 3 , α-FeOOOH, and Fe 3 O 4 , comprising the sequential steps of (a) adding to the said acicular particles of the iron compound titanium, in the form of TiO(OH) 2 or TiO 2 , and tin, in the form of Sn(OH) 2 or SnO(OH) 2 ; (b) thereafter subjecting same to at least one treatment in air at 400°-550° C,; and finally (c) subjecting the mixture to reductionat 340°-420° C with a gas containing more than 50% by volume of hydrogen; the titanium being introduced into the particles of the iron compound in an amount of 0.5 - 1% by weight, calculated as TiO 2 , and the tin being introduced in an amount of 3 - 6% by weight, these percentages being referred to pure iron.
Claim 2
Dependent Claim
160 words
A process for preparing metallic powders based on iron and suitable for magnetic recording, starting from acicular particles of an iron compound selected from the class consisting of α-Fe 2 O 3 , α-FeOOOH, and Fe 3 O 4 , comprising the sequential steps of (a) adding to the said acicular particles of the iron compound titanium, in the form of TiO(OH) 2 or TiO 2 , and tin, in the form of Sn(OH) 2 or SnO(OH) 2 ; (b) thereafter subjecting same to at least one treatment in air at 400°-550° C,; and finally (c) subjecting the mixture to reductionat 340°-420° C with a gas containing more than 50% by volume of hydrogen; the titanium being introduced into the particles of the iron compound in an amount of 0.5 - 1% by weight, calculated as TiO 2 , and the tin being introduced in an amount of 3 - 6% by weight, these percentages being referred to pure iron.
Claim 3
Dependent Claim
78 words
A process according to claim 1, wherein the titanium is introduced by: preparing a suspension of α-Fe 2 O 3 , α-FeOOH or Fe 3 O 4 in ethyl alcohol; adding an alcoholic solution of TiCl 4 l in an amount varying according to the amount of titanium to be introduced; precipitating TiO(OH) 2 , at a temperature ranging from room temperature to 60° C, by the addition of water; and filtering, washing and drying the resulting mass.
Claim 4
Dependent Claim
77 words
A process according to claim 1, wherein the titanium is introduced by: preparing a fluid paste of α-Fe 2 O 3 , α-FeOOH or Fe 3 O 4 in ethyl alcohol; adding a titanium organic salt in alcoholic solution, in an amount varying according to the percentage of titanium to be introduced; impregnating the iron compound with the titanium organic salt at a temperature ranging from room temperature to 60° C; and drying the mass so obtained.
Claim 5
Dependent Claim
93 words
A process according to claim 1, wherein the tin is introduced by: preparing a suspension of α-Fe 2 O 3 , α-FeOOH or Fe 3 O 4 in water; adding an acid solution of a tin salt in an amount varying according to the percentage of tin to be introduced; precipitating Sn(OH) 2 or SnO(OH) 2 at a temperature between room temperature and 60° C, bringing the pH to a value ranging from 3 to 5 by the addition of NH 4 OH or NaOH; and filtering, washing and drying the thus-obtained mass.
Claim 6
Dependent Claim
78 words
A process according to claim 1, wherein in step (a) the acicular particles of the iron compound are treated not only with titanium and tin, but also with cobalt and/or silica; the cobalt being introduced into the particles of iron compound in an amount not exceeding 6% by weight with respect to pure iron, and the silica being introduced into the particles of iron compound in an amount not exceeding 5% by weight with respect to pure iron.
Claim 7
Dependent Claim
66 words
A process according to claim 5, wherein the cobalt is introduced by: preparing a fluid paste of α-Fe 2 O 3 , αFeOOH or Fe 3 O 4 in water; adding a cobalt acetate solution in an amount varying according to the percentage of cobalt to be introduced; heating the mass to 50°-80° C, under stirring, until it becomes pasty; and drying the mass thus obtained.
Claim 8
Dependent Claim
91 words
A process according to claim 5, wherein the silica is introduced by: preparing a suspension of α-Fe 2 O 3 , α-FeOOH or Fe 3 O 4 in water; adding an aqueous solution of Na 2 SiO 3 in an amount varying according to the percentage of SiO 2 to be introduced; precipitating SiO 2 at a temperature ranging from room temperature to 60° C, bringing the pH to a value not exceeding 6 by addition of HCl or HNO 3 ; and filtering, washing and drying the mass thus obtained.
Claim 9
Dependent Claim
18 words
A process according to claim 1, wherein the tin is introduced prior to the introduction of the titanium.
Claim 10
Dependent Claim
18 words
Metallic powders based on iron suitable for magnetic recording, when prepared by a process according to claim 1.