Yttrium fluoride spray material, yttrium oxyfluoride-deposited article, and making methods

Abstract

An yttrium fluoride spray material contains Y.sub.5O.sub.4F.sub.7 and YF.sub.3, and has an average particle size of 10-60 m and a bulk density of 1.2-2.5 g/cm.sup.3. The Y.sub.5O.sub.4F.sub.7 and YF.sub.3 in the yttrium fluoride spray material consist of 30 to 90% by weight of Y.sub.5O.sub.4F.sub.7 and the balance of YF.sub.3. A sprayed coating of yttrium oxyfluoride is obtained by atmospheric plasma spraying of the spray material.

Claims

1. A spray material comprising yttrium compounds, the yttrium compounds consisting of 30 to 71% by weight of Y.sub.5O.sub.4F.sub.7 and the balance 29 to 70% by weight of YF.sub.3, with respect to the total of Y.sub.5O.sub.4F.sub.7 and YF.sub.3, and the spray material having an average particle size of 10 to 60 m and a bulk density of 1.2 to 2.5 g/cm.sup.3.

2. The spray material of claim 1 having an average particle size of 33 to 60 m.

3. The spray material of claim 2 having an aspect ratio of up to 2.

4. The spray material of claim 2 having an angle of repose of up to 45.

5. The spray material of claim 2 obtained by a method comprising the steps of: mixing 10 to 50% by weight of yttrium oxide having an average particle size of 0.01 to 3 m with the balance of the ammonium fluoride complex salt of formula: (YF.sub.3).sub.3NH.sub.4F.H.sub.2O having an average particle size of 0.01 to 3 m, and granulating and firing the mixture.

6. The spray material of claim 1 having an aspect ratio of up to 2.

7. The spray material of claim 1 having an angle of repose of up to 45.

8. The spray material of claim 1 obtained by a method comprising the steps of: mixing 10 to 50% by weight of yttrium oxide having an average particle size of 0.01 to 3 m with the balance of the ammonium fluoride complex salt of formula: (YF.sub.3).sub.3NH.sub.4F.H.sub.2O having an average particle size of 0.01 to 3 m, and granulating and firing the mixture.

Description

EXAMPLE

(1) Examples are given below by way of illustration and not by way of limitation. In Table, wt % is percent by weight.

Reference Example 1

(2) Preparation of Ammonium Fluoride Complex Salt

(3) A 1 mol/L yttrium nitrate solution, 1 L, was heated at 50 C. and mixed with 1 L of a 1 mol/L acidic ammonium fluoride solution at 50 C. for about 30 minutes with stirring. A white precipitate crystallized out. The precipitate was filtered, washed with water and dried. On X-ray diffractometry analysis, it was identified to be an ammonium fluoride complex salt of formula: (YF.sub.3).sub.3NH.sub.4F.H.sub.2O. It had an average particle size of 0.7 m as measured by laser light diffractometry.

Examples 1 to 5 and Comparative Examples 1 and 2

(4) Preparation of Spray Powder (Spray Material)

(5) A spray powder material was obtained by mixing predetermined amounts of ingredients to form a mix as shown in Table 1, dispersing the mix in water, with adding a binder in Examples 1 to 4 and Comparative Examples 1 and 2 or without adding a binder in Example 5, shown in Table 1 to form a slurry, granulating by means of a spray dryer, and firing under the conditions shown in Table 1. The resulting spray powder was identified and measured for crystal structure, particle size distribution, bulk density, angle of repose, and yttrium, fluorine, oxygen, carbon and nitrogen concentrations. The results are shown in Table 1. Notably, the identification was performed by X-ray diffractometry, the particle size distribution was measured by laser light diffractometry, the bulk density and angle of repose were measured by a powder tester, yttrium concentration was analyzed by ethylenediamine tetraacetic acid (EDTA) titration method of dissolved samples, the fluorine concentration was analyzed by dissolution ion chromatography, and the oxygen, carbon and nitrogen concentrations were analyzed by the infrared (IR) method after combustion. In each of Examples 1-5 and Comparative Examples 1 and 2, carbon and nitrogen were not detected, i.e., carbon and nitrogen concentrations were 0 wt %, respectively. Each of contents of the yttrium compound components was determined as follows. In Examples 1 to 5 and Comparative Example 1, Y.sub.5O.sub.4F.sub.7 content was calculated based on the oxygen concentration, and YF.sub.3 content was calculated as the balance. In Comparative Example 2, content of each of three substances (crystalline phases), which was identified by X-ray diffractometry, was calculated from scale factors of the crystalline phases.

(6) Preparation of Sprayed Article

(7) Each of the spray powder materials in Examples 1 to 5 and Comparative Examples 1 and 2 was deposited onto an aluminum substrate by atmospheric plasma spraying using a gas mixture of 40 L/min of argon and 5 L/min of hydrogen with air as an ambient gas. The deposited article (sprayed member) had a sprayed coating of about 200 m thick. The sprayed coating was scraped off the coated article. The sprayed coating was identified by X-ray diffractometry, and analyzed for yttrium concentration by ethylenediamine tetraacetic acid (EDTA) titration method of dissolved samples, fluorine concentration by dissolution ion chromatography, and oxygen concentrations by the combustion IR method. The results are shown in Table 2.

(8) In Examples 1 to 5, the yttrium fluoride spray material which had been prepared by mixing 10 to 50% by weight, of yttrium oxide with the balance of ammonium fluoride complex salt of (YF.sub.3).sub.3NH.sub.4F.H.sub.2O, granulating and firing was a mixture of 30 to 90% by weight of Y.sub.5O.sub.4F.sub.7 and the balance of YF.sub.3. When the spray material was deposited onto an aluminum substrate by atmospheric plasma spraying using a gas mixture of 40 L/min of argon and 5 L/min of hydrogen with air as an ambient gas, the sprayed coating consisted of at least one yttrium oxyfluoride selected from among YOF, Y.sub.5O.sub.4F.sub.7, and Y.sub.7O.sub.6F.sub.9.

(9) In Comparative Examples 1 and 2, the yttrium fluoride spray material was prepared by mixing predetermined amounts of yttrium oxide (Y.sub.2O.sub.3) and yttrium fluoride (YF.sub.3), granulating and firing. When the spray material was deposited onto an aluminum substrate by atmospheric plasma spraying using a gas mixture of 40 L/min of argon and 5 L/min of hydrogen with air as an ambient gas and deposited article was obtained, the sprayed coating contained Y.sub.2O.sub.3.

(10) The deposited articles of Examples 1 to 5 and Comparative Examples 1 and 2 were washed with running pure water at a flow rate of 100 L/hr before they were immersed in 10 L of pure water for 10 minutes under ultrasonic agitation. To the collected immersion solution, 100 mL of 2 mol/L nitric acid was added. The yttrium content of the solution was measured by ICP. The results are shown in Table 3.

(11) TABLE-US-00001 TABLE 1 Comparative Example Example 1 2 3 4 5 1 2 Ingredients, Y.sub.2O.sub.3 (D50 = 0.3 m) particle size, 20 wt % 30 wt % 40 wt % 50 wt % 20 wt % 10 wt % 50 wt % and mixing ratio (YF.sub.3).sub.3NH.sub.4FH.sub.2O (D50 = 0.7 m) YF.sub.3 (D50 = 1.4 m) 80 wt % 70 wt % 60 wt % 50 wt % 80 wt % 90 wt % 50 wt % Granulation Mix 25 wt % 25 wt % 25 wt % 25 wt % 25 wt % 25 wt % 25 wt % conditions Binder* CMC CMC PVA PVP none CMC CMC 8 wt % 8 wt % 8 wt % 8 wt % 8 wt % 8 wt % Firing Atmos- N.sub.2 vacuum N.sub.2 N.sub.2 N.sub.2 N.sub.2 N.sub.2 conditions phere Temper- 800 C. 900 C. 900 C. 800 C. 800 C. 800 C. 800 C. ature Analysis of spray powder Particle D10, m 23 18 25 21 23 22 23 size D50, m 37 28 38 33 37 37 34 distribution D90, m 54 48 65 47 54 59 64 Bulk density, g/cm.sup.3 1.3 1.6 1.7 1.3 1.3 1.3 1.4 Angle of repose, 39 38 36 39 39 42 41 Y concentration, wt % 66.9 68.4 67.4 67.9 68.9 65.6 72.7 F concentration, wt % 28.8 24.5 24.6 22.9 28.0 32.1 16.4 O concentration, wt % 4.3 7.1 8.0 9.2 4.3 2.3 10.9 X-ray diffraction Y.sub.5O.sub.4F.sub.7 Y.sub.5O.sub.4F.sub.7 Y.sub.5O.sub.4F.sub.7 Y.sub.5O.sub.4F.sub.7 Y.sub.5O.sub.4F.sub.7 Y.sub.5O.sub.4F.sub.7 Y.sub.5O.sub.4F.sub.7 analysis 43 wt % 71 wt % 80 wt % 92 wt % 43 wt % 23 wt % 87 wt % YF.sub.3 YF.sub.3 YF.sub.3 YF.sub.3 YF.sub.3 YF.sub.3 YF.sub.3 57 wt % 29 wt % 20 wt % 8 wt % 57 wt % 77 wt % 9 wt % Y.sub.2O.sub.3 4 wt % *CMC: carboxymethyl cellulose, PVA: polyvinyl alcohol, PVP: polyvinyl pyrrolidone

(12) TABLE-US-00002 TABLE 2 Analysis of Comparative sprayed Example Example coating 1 2 3 4 5 1 2 Y concen- 66 69.6 72.4 71.5 66 66 73 tration, wt % F concen- 26.7 21.4 16.6 15 26.7 30.4 14.3 tration, wt % O concen- 7.3 9 11 13.5 7.3 3.6 12.7 tration, wt % X-ray Y.sub.5O.sub.4F.sub.7 Y.sub.5O.sub.4F.sub.7 Y.sub.5O.sub.4F.sub.7 YOF Y.sub.5O.sub.4F.sub.7 Y.sub.5O.sub.4F.sub.7 YOF diffraction YOF YOF YOF YOF YF.sub.3 Y.sub.2O.sub.3 analysis Y.sub.2O.sub.3

(13) TABLE-US-00003 TABLE 3 Comparative Simple particle Example Example test 1 2 3 4 5 1 2 Y concentration, 3 5 7 10 3 20 30 mg/L

(14) Japanese Patent Application No. 2015-208616 is incorporated herein by reference.

(15) Although some preferred embodiments have been described, many modifications and variations may be made thereto in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims.