Industrial method for producing dispersion-strengthened iron-based materials at low cost and in large-scale

Abstract

The invention provides an industrial method for producing dispersion-strengthened iron-based materials at low cost and in large-scale. The industrial acid pickling waste solution is treated by spray roasting process after yttrium chloride is added. During the spray roasting process, the solution is atomized into fine droplets, the droplets are contacted with gas and dried into powders, which are heated in air to form metal oxides. The mixed powders of the metal oxides are reduced in hydrogen stream to obtain yttria dispersion-strengthened iron powders. High performance dispersion-strengthened iron materials are obtained by densifying the yttria dispersion-strengthened iron powders. The method has simple process and low cost, and is suitable for large-scale production due to the direct use of acid pickling waste solution from steel factory.

Claims

1. A method for industrially producing an iron-based strengthened dispersion material, wherein: step 1, adding yttrium chloride into a waste hydrochloric acid pickling liquor containing iron to obtain waste pickling liquor containing matrix metal ions and dispersed-phase metal ions; step 2, transferring the waste pickling liquor containing matrix metal ions and dispersed-phase metal ions into a preconcentrator, and concentrating the waste pickling liquor containing matrix metal ions and dispersed-phase metal ions to obtain a concentrated waste pickling liquor; step 3, atomizing the concentrated waste pickling liquor into tiny droplets by spraying the concentrated waste pickling liquor through a nozzle on the top of a roasting furnace, roasting the tiny droplets to obtain an oxide mixture of ferric oxide and yttrium oxide, wherein particles of ferric chloride in the concentrated pickling liquid are roasted into free hydrogen chloride and iron oxide in a burning gas, and yttrium chloride is roasted into free hydrogen chloride and yttrium oxide; step 4, reducing the oxide mixture in H.sub.2 atmosphere at 900-1000 C. for 60-90 minutes to obtain strengthened dispersion iron powders with yttrium oxide as a dispersed phase; and step 5, densifying the strengthened dispersion iron powders with yttrium oxide by a cold-pressing sintering process or a hot extrusion process to obtain the iron-based strengthened dispersion material, wherein the matrix metal ions result in elemental metal, and the dispersed-phase metal ions result in dispersed-phase oxide.

2. The method for industrially producing the iron-based strengthened dispersion material of claim 1 wherein the cold-pressing sintering process is including: a. molding the strengthened dispersion iron powders with yttrium oxide by cold pressing to obtain a molded strengthened dispersion iron powders, wherein, in the process of molding by cold pressing, a mold pressing or a cold isostatic pressing is adopted, pressure of the mold pressing is 600-1200 Mpa, pressure of the cold isostatic pressing is in a range of 200-300 MPa, pressure holding time is in a range of 30-90 minutes; b. performing vacuum sintering on the molded strengthened dispersion iron powders, wherein the sintering temperature is in a range of 1300-1400 C., the temperature is maintained for 60-120 minutes, and the vacuum degree is in a range of 0.1-0.01 Pa.

3. The method for industrially producing the iron-based strengthened dispersion material of claim 1, wherein the hot extrusion process including: loading the strengthened dispersion iron powders with yttrium oxide into a can, and heating it to 1150-1250 C. for hot extrusion after vacuuming under a vacuum degree of 10.sup.1-10.sup.2 pa for 1-2 hours, so that the strengthened dispersion iron powders are solidified.

4. The method for industrially producing the iron-based strengthened dispersion material of claim 1, wherein the waste hydrochloric acid pickling liquor has an iron concentration in a range of 50-150 g/L.

5. The method for industrially producing the iron-based strengthened dispersion material of claim 1, wherein the concentrated waste pickling liquor has an iron concentration in a range of 600-1500 g/L.

6. The method for industrially producing the iron-based strengthened dispersion material of claim 1, wherein the spraying has a speed of 200-4000 L/h; and the temperature in the roasting furnace is in a range of 300 C. -700 C.

7. The method for industrially producing the iron-based strengthened dispersion material of claim 6 wherein the spraying has a speed of 1000-3000 L/h.

Description

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) Embodiment 1: 0.1% Y.sub.2O.sub.3 dispersion strengthened iron material

(2) yttrium chloride is added into a hydrochloric acid pickling waste liquor (concentration of iron in the pickling waste liquor is 50 g/L), so as to obtain a pickling waste liquor containing matrix metal ions, by which, a metal elementary substance is finally generated, and dispersed-phase metal ions, by which, an oxide as a dispersed phase is finally generated. When raw materials are converted into quality of the oxide as the dispersed phase and the matrix metal, mass fraction of the oxide as the dispersed phase in the total alloy is 0.1%; Let the pickling waste liquor containing matrix metal ions and dispersed-phase metal ions get into a preconcentrator, so as to concentrate the waste acid, and the concentration of iron after concentrating is 600 g/L; The concentrated waste acid is atomized and sprayed to be tiny droplets by a nozzle on the top of a roasting furnace, the spray speed of the concentrated waste acid being 600 L/h, the temperature in the spray roasting furnace being 400 C. A mixture of particles of ferric chloride and ferrous chloride in the concentrated acid is roasted into free hydrogen chloride and iron oxide in a burning gas, and yttrium chloride is roasted into free hydrogen chloride and yttrium oxide; Mixed oxides are reduced in H.sub.2 atmosphere at 900 C., with a reduction time of 90 minutes, so as to get dispersion strengthened iron powders with yttrium oxide as the dispersed phase; The dispersion strengthened iron powders are molded by mold pressing, with a pressing pressure of 600 Mpa, and a vacuum sintering process is used, the sintering temperature being 1300 C. and maintained for 120 minutes. As for the prepared dispersion strengthened iron material, the relative density is 97.5%, the tensile strength at room temperature is 363 MPa, and the HRB hardness is 70.
Embodiment 2:0.5% Y.sub.2O.sub.3 dispersion strengthened iron material yttrium chloride is added into a hydrochloric acid pickling waste liquor (concentration of iron in the pickling waste liquor is 90 g/L), so as to obtain a pickling waste liquor containing matrix metal ions, by which, a metal elementary substance is finally generated, and dispersed-phase metal ions, by which, an oxide as a dispersed phase is finally generated. When raw materials are converted into quality of the oxide as the dispersed phase and the matrix metal, mass fraction of the oxide as the dispersed phase in the total alloy is 0.5%; Let the pickling waste liquor containing matrix metal ions and dispersed-phase metal ions get into a preconcentrator, so as to concentrate the waste acid, and the concentration of iron after concentrating is 900 g/L; The concentrated waste acid is atomized and sprayed to be tiny droplets by a nozzle on the top of a roasting furnace, the spray speed of the concentrated waste acid being 2000 L/h, the temperature in the spray roasting furnace being 700 C. A mixture of particles of ferric chloride and ferrous chloride in the concentrated acid is roasted into free hydrogen chloride and iron oxide in a burning gas, and yttrium chloride is roasted into free hydrogen chloride and yttrium oxide; Mixed oxides are reduced in H.sub.2 atmosphere at 900 C., with a reduction time of 90 minutes, so as to get dispersion strengthened iron powders with yttrium oxide as the dispersed phase; The dispersion strengthened iron powders are loaded into a canning, which is vacuumized under a vacuum degree of 10.sup.2 pa for 2 hours firstly, and heated to 1200 C. for hot extrusion, so that the dispersion strengthened iron powders are densified. As for the prepared dispersion strengthened iron material, the relative density is 99%, the tensile strength at room temperature is 540 MPa, and the HRB hardness is 92.
Embodiment 3:1.0% Y.sub.2O.sub.3 Dispersion Strengthened Iron Material yttrium chloride is added into a hydrochloric acid pickling waste liquor (concentration of iron in the pickling waste liquor is 100 g/L), so as to obtain a pickling waste liquor containing matrix metal ions, by which, a metal elementary substance is finally generated, and dispersed-phase metal ions, by which, an oxide as a dispersed phase is finally generated. When raw materials are converted into quality of the oxide as the dispersed phase and the matrix metal, mass fraction of the oxide as the dispersed phase in the total alloy is 1%; Let the pickling waste liquor containing matrix metal ions and dispersed-phase metal ions get into a preconcentrator, so as to concentrate the waste acid, and the concentration of iron after concentrating is 1000 g/L; The concentrated waste acid is atomized and sprayed to be tiny droplets by a nozzle on the top of a roasting furnace, the spray speed of the concentrated waste acid being 3000 L/h, the temperature in the spray roasting furnace being 600 C. A mixture of particles of ferric chloride and ferrous chloride in the concentrated acid is roasted into free hydrogen chloride and iron oxide in a burning gas, and yttrium chloride is roasted into free hydrogen chloride and yttrium oxide; Mixed oxides are reduced in H.sub.2 atmosphere at 950 C., with a reduction time of 75 minutes, so as to get dispersion strengthened iron powders with yttrium oxide as the dispersed phase; The dispersion strengthened iron powders are molded by cold isostatic pressing, the pressing pressure being 200 Mpa, the pressure holding time being 60 minutes, and a vacuum sintering process is used, the sintering temperature being 1400 C. and being maintained for 120 minutes. As for the prepared dispersion strengthened iron material, the relative density is 98%, the tensile strength at room temperature is 430 MPa, and the HRB hardness is 86.
Embodiment 4:2.0% Y.sub.2O.sub.3 Dispersion Strengthened Iron Material yttrium chloride is added into a hydrochloric acid pickling waste liquor (concentration of iron in the pickling waste liquor is 150 g/L), so as to obtain a pickling waste liquor containing matrix metal ions, by which, a metal elementary substance is finally generated, and dispersed-phase metal ions, by which, an oxide as a dispersed phase is finally generated. When raw materials are converted into quality of the oxide as the dispersed phase and the matrix metal, mass fraction of the oxide as the dispersed phase in the total alloy is 2%; Let the pickling waste liquor containing matrix metal ions and dispersed-phase metal ions get into a preconcentrator, so as to concentrate the waste acid, and the concentration of iron after concentrating is 1500 g/L; The concentrated waste acid is atomized and sprayed to be tiny droplets by a nozzle on the top of a roasting furnace, the spray speed of the concentrated waste acid being 4000 L/h, the temperature in the spray roasting furnace being 700 C. A mixture of particles of ferric chloride and ferrous chloride in the concentrated acid is roasted into free hydrogen chloride and iron oxide in a burning gas, and yttrium chloride is roasted into free hydrogen chloride and yttrium oxide; Mixed oxides are reduced in H.sub.2 atmosphere at 1000 C., with a reduction time of 60 minutes, so as to get dispersion strengthened iron powders with yttrium oxide as the dispersed phase; The dispersion strengthened iron powders are loaded into a canning, which is vacuumized under a vacuum degree of 10.sup.2 pa for 2 hours firstly, and heated to 1250 C. for hot extrusion, so that the dispersion strengthened iron powders are densified.

(3) As for the prepared dispersion strengthened iron material, the relative density is 99%, the tensile strength at room temperature is 710 MPa, and the HRB hardness is 103.