Method for the particle size independent spectrometric determination of metal particles in lubricating oils and hydraulic fluids

• US 4,448,887 A
• Filed: 09/30/1982
• Issued: 05/15/1984
• Est. Priority Date: 09/30/1982
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Kauffman, Robert E., Saba, Costandy S., Rhine, Wendell E.
• Primary Examiner(s): Turk, Arnold
• Assistant Examiner(s): Hill, Jr., Robert J.
• Application Number:
  US06/429,939
• Time in Patent Office: 593 Days
• Field of Search: 436/60, 436/73, 436/153, 436/154, 436/171, 436/175, 73/64, 356/36, 356/70
• US Class Current: 436/60
• CPC Class Codes: G01N 33/2858 Metal particles
• CPC Class Codes: Y10T 436/25125 Digestion or removing interfering materials

Abstract

The degree of wear metal contamination in an oil is determined by treating a sample of the oil with a mixture of HF/HCl/nitric acid, diluting the oil/acid mixture with a solvent mixture consisting of a nonionic surfactant and a diluent, and spectrometrically analyzing the resulting diluted mixture. Severe wear in an oil wetted apparatus may be detected by directly analyzing spectrometrically a sample of the oil and comparing the results of such analysis with the results obtained according to the acid dissolution method described above.

Claims

1. A method for determining the degree of wear metal contamination of an oil which comprises the steps of:

(a) combining a sample of said oil with an acid mixture consisting of about 8 to 12 weight percent of concentrated HF, about 76 to 84 weight percent of concentrated HCl and about 8 to 12 weight percent of concentrated nitric acid;

(b) heating the resulting oil/acid mixture to dissolve wear metal particles;

(c) diluting said oil/acid mixture with a solvent mixture consisting of about 20 to 40 parts by weight of a nonionic surfactant and about 60 to 80 parts of a diluent; and

(d) spectrometrically analyzing the resulting diluted mixture.

2. The method of claim 1 wherein said acid mixture consists of about 10 weight percent HF, about 80 weight percent HCl and about 10 weight percent nitric acid.

3. The method of claim 1 wherein said diluent is selected from the group consisting of kerosene and methyl isobutyl ketone.

4. The method of claim 1 wherein said surfactant has the general formula

5. The method of claim 4 wherein R has an average of 10 carbon atoms and n has an average value of 6.

6. The method of claim 5 wherein said solvent mixture consists of 35 parts of said surfactant and 65 parts of kerosene.

7. The method of claim 5 wherein said solvent mixture consists of 25 parts of said surfactant and 75 parts of methyl isobutyl ketone.

8. The method of claim 1 wherein said oil/acid mixture is heated, with stirring, for about 5 minutes at a temperature in the approximate range of 20°

to 70°

C.

9. The method of claim 1 wherein said oil sample is mixed with said acid mixture in a ratio ranging from 4:

1 to 6;

1 by weight, and the oil/acid mixture is diluted with said solvent mixture in a ratio of at least 1;

2, by weight.

10. The method of claim 9 wherein said oil:

acid ratio is 5;

1 and said oil/acid;

solvent ratio is 1;

4.

11. A method for detecting severe wear at an early stage in an oil wetted apparatus which comprises the steps of:

(a) obtaining a sample of oil from said apparatus;

(b) spectrometrically analyzing a first portion of said sample;

(c) treating a second portion of said sample with an acid mixture consisting of about 8 to 12 weight percent concentrated HF, about 76 to 84 weight percent concentrated HCl and about 8 to 12 weight percent concentrated nitric acid;

(d) heating the resulting oil/acid mixture to dissolve wear metal particles;

(e) diluting said oil/acid mixture with a solvent mixture consisting of about 20 to 40 parts by weight of a nonionic surfactant and about 60 to 80 parts of a diluent;

(f) spectrometrically analyzing the resulting diluted mixture; and

(g) comparing the results obtained according to step (b) with the results obtained according to step (f).

12. The method of claim 11 wherein said acid mixture consists of about 10 weight percent HF, about 80 weight percent HCl and about 10 weight percent nitric acid.

13. The method of claim 11 wherein said diluent is selected from the group consisting of kerosene and methyl isobutyl ketone.

14. The method of claim 11 wherein said surfactant has the general formula

15. The method of claim 14 wherein R has an average of 10 carbon atoms and n has an average value of 6.

16. The method of claim 15 wherein said solvent mixture consists of 35 parts of said surfactant and 65 parts of kerosene.

17. The method of claim 15 wherein said solvent mixture consists of 25 parts of said surfactant and 75 parts of methyl isobutyl ketone.

18. The method of claim 11 wherein said acid/oil mixture is heated, with stirring, for about 5 minutes at a temperature in the approximate range of 20°

to 70°

C.

19. The method of claim 11 wherein said second portion is mixed with said acid mixture in a ratio ranging from 4:

1 to 6;

1, by weight, and the oil/acid mixture is diluted with said solvent mixture in a ratio of at least 1;

2, by weight.

20. The method of claim 19 wherein said oil:

acid ratio is 5;

1 and said oil/acid;

solvent ratio is 1;

4.