US3546452A - Method of producing samples for x-ray fluorescence analysis - Google Patents
Method of producing samples for x-ray fluorescence analysis Download PDFInfo
- Publication number
- US3546452A US3546452A US652027A US3546452DA US3546452A US 3546452 A US3546452 A US 3546452A US 652027 A US652027 A US 652027A US 3546452D A US3546452D A US 3546452DA US 3546452 A US3546452 A US 3546452A
- Authority
- US
- United States
- Prior art keywords
- vitreous body
- crucible
- ray fluorescence
- holder
- fluorescence analysis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title description 17
- 238000004458 analytical method Methods 0.000 title description 15
- 238000004876 x-ray fluorescence Methods 0.000 title description 10
- 210000004127 vitreous body Anatomy 0.000 description 29
- 229910021538 borax Inorganic materials 0.000 description 10
- 238000001816 cooling Methods 0.000 description 10
- 239000004328 sodium tetraborate Substances 0.000 description 10
- 235000010339 sodium tetraborate Nutrition 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- 239000011324 bead Substances 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 229910002804 graphite Inorganic materials 0.000 description 6
- 239000010439 graphite Substances 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 239000000155 melt Substances 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- JUWSSMXCCAMYGX-UHFFFAOYSA-N gold platinum Chemical compound [Pt].[Au] JUWSSMXCCAMYGX-UHFFFAOYSA-N 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 210000002268 wool Anatomy 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910001260 Pt alloy Inorganic materials 0.000 description 1
- 229910000629 Rh alloy Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-M bisulphate group Chemical group S([O-])(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-M 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 210000003128 head Anatomy 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- -1 platinum-gold (-5) Chemical compound 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 229910000162 sodium phosphate Inorganic materials 0.000 description 1
- 239000001488 sodium phosphate Substances 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/2202—Preparing specimens therefor
Definitions
- ABSTRACT OF THE DISCLOSURE A method of producing a sample suitable for X-ray analysis in which a mixture of the substance and a vitreous material is formed, melted, and after melting is cooled to form a body. During cooling an electric current is passed through the body in the direction of a holder to free the body from the holder.
- the invention relates to a method of producing samples for analysis, particularly samples to be examined by means of the X-ray fluorescence spectrometric analysing method (termed hereinafter the X-ray fluorescence analysis).
- the examination-frequently a quantitative analysis of substances by X-ray fluorescence analysis requires the samples to be provided in an appropriate shape.
- a method in which the substance to be examined for example, a mineral, is mixed with borax, the mixture being heated until a homogeneous melt is obtained, which is subsequently cooled so that a vitreous body, the known borax bead, is obtained.
- this borax head should have definite dimensions suitable for the geometry of the apparatus employed for the analysis.
- the borax bead is usually made in a crucible of graphite, platinum or a platinum alloy.
- a drawback in the production of analysis samples in this way is that the vitreous body (the borax bead) sticks to the Wall of the crucible. Efforts have been made to obviate this drawback by rapid cooling of the crucible. The result thereof is adversely affected, when the bottom and/ or the wall of the crucible are rough. A further disadvantage resides in that owing to the rapid cooling strong local stresses are produced in the vitreous body, which may give rise to cracking.
- the invention relates to a method of producing samples for analysis, in which a mixture of the substance to be tested and a substance, from which a vitreous body is formed by melting and subsequent cooling, is heated in or on a holder of electrically conductive material until the mixture is melted, after which it is cooled, and is characterized in that during the cooling of the vitreous body electric current is passed through the body towards the holder until the vitreous body no longer adheres to the holder.
- the current may be passed through the vitreous body towards the holder in various ways.
- the holder may be connected to the negative terminal of a direct-voltage source, while an electrode, for example, of graphite wool, connected to the positive terminal, is pressed against the vitreous body. It has been found that the desired effect may furthermore be obtained by means of alternating current. In the interface between the vitreous body and the holder a blocking effect is produced so that, when alternating voltage is used, current is passed only in one direction, i.e. from the body to the holder.
- the voltage to be used for the passage of current depends to some extent upon the material used for the vitreous body. It depends more intimately upon the temperature of said body at which the current starts passing through, owing to the intimate relationship between its resistance and temperature. It is advantageous to start the passage of current at a temperature at which the vitreous body is still viscous; with the frequently employed borax bead this is at about 600 C. to 700 C. In this case a voltage of 110 to 220 v. is suitable.
- the current can be advantageously passed through the vitreous body to the holder by means of spark discharge or voltage flash-over.
- the spark discharge or the voltage flash-over may be achieved in known manner, for example, by holding a pointed electrode, connected to a voltage source of, for example, 50 kv., at a given distance, for example, 2 ems. above the vitreous body and by connecting the crucible to earth.
- the voltage flash-over has to take place through the bead towards the crucible.
- the spark discharge is produced by direct voltage, the electrode above the vitreous body has to be connected to the positive terminal of the voltage source. It has been found that the spark discharge may also be produced by means. of alternating voltage. Due to the blocking effect in the interface between the vitreous body and the crucible the flash-over is also in this case produced only in one direction. The process of the disengagement of the vitreous body during the spark discharge can be observed visually and it can be assessed when the process has finished. It can thus be ascertained in a simple manner when the spark discharge can be finished.
- the spark discharge when the resistance of the vitreous body is still fairly low; this is the case, when the vitreous body is still at a higher temperature. Therefore, it is preferred to start the spark discharge when the vitreous body is still viscous. If borax is used, this is at 600 C. to 700 C. The discharge may be terminated, for example, at about 200 C. The spark discharge may also be started at a lower temperature than about 700 C. These values are not very critical. Also for this reason the method according to the invention contributes to the possibility of carrying out the X-ray fluorescence analysis automatically. Automation of the X-ray fluorescence analysis is essential for many industries, inter alia for the cement industry, in connection with the fact that frequently a very great number of samples has to be examined within a short period of time.
- the holder is usually a crucible of conventional material, such as platinum, platinum-gold and graphite (electro-graphite, pyrolytic graphite).
- the substance forming, subsequent to melting and cooling, a vitreous body may be a known substance, for example, an alkali-tetra-borate, for instance borax, a phosphate and a bisulphate.
- borax 4 parts by weight of borax were mixed with 1 part by weight of lime and stone (the substance to be tested). The mixture was melted in a crucible of platinum-gold (-5) by heating at about 1000 C. After the mass had completely melted, it was cooled in air. Above the melt was arranged a pointed electrode, connected to an alternating-voltage source of 50 kv., so that the distance between the electrode and the surface of the melt was about 2 ems. The crucible was connected to earth. The spark discharge was started at a temperature of about 700 C. of the vitreous body formed from the melt; during cooling the discharge was continued until the vitreous body had completely disengaged from the wall of the crucible. This took about 3 minutes.
- the method can be improved in that during the spark discharge the latter is surrounded by a stream of a gas, for example air.
- a gas for example air.
- the direction of the stream should be from the electrode to the holder of the sample. This intprovement effects that the glass bead is disengaged from the holder in a shorter period of time. In many examples the disengagement of the sample was effected within 30 seconds.
- a method of producing samples for X-ray fluorescence analysis comprising the steps of forming a mixture of a substance to be tested and a substance from which a vitreous body is formed by melting, heating said mixture while in contact with a holder of electrically conductive material until the mixture is melted, thereafter cooling the melted material to form a vitreous body, and passing an electric current through this body during cooling toward the holder until the vitreous body no longer adheres to the holder.
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
- Sampling And Sample Adjustment (AREA)
Description
United States Patent 3,546,452 METHOD OF PRODUCING SAMPLES FOR X-RAY FLUORESCENCE ANALYSIS Popko Reinder Dijksterhuis and Hermanus Arnoldus Verharen, Emmasingel, Eindhoven, Netherlands, assignors, by mesne assignments, to U.S. Philips Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed July 10, 1967, Ser. No. 652,027 Claims priority, application Netherlands, July 9, 1966, 6609665 Int. Cl. G01n 23/22 US. Cl. 250--51.5 4 Claims ABSTRACT OF THE DISCLOSURE A method of producing a sample suitable for X-ray analysis in which a mixture of the substance and a vitreous material is formed, melted, and after melting is cooled to form a body. During cooling an electric current is passed through the body in the direction of a holder to free the body from the holder.
The invention relates to a method of producing samples for analysis, particularly samples to be examined by means of the X-ray fluorescence spectrometric analysing method (termed hereinafter the X-ray fluorescence analysis).
The examination-frequently a quantitative analysis of substances by X-ray fluorescence analysis requires the samples to be provided in an appropriate shape. There is known, for example, a method in which the substance to be examined, for example, a mineral, is mixed with borax, the mixture being heated until a homogeneous melt is obtained, which is subsequently cooled so that a vitreous body, the known borax bead, is obtained. For the X-ray fluorescence analysis this borax head should have definite dimensions suitable for the geometry of the apparatus employed for the analysis.
The borax bead is usually made in a crucible of graphite, platinum or a platinum alloy.
A drawback in the production of analysis samples in this way is that the vitreous body (the borax bead) sticks to the Wall of the crucible. Efforts have been made to obviate this drawback by rapid cooling of the crucible. The result thereof is adversely affected, when the bottom and/ or the wall of the crucible are rough. A further disadvantage resides in that owing to the rapid cooling strong local stresses are produced in the vitreous body, which may give rise to cracking.
It has furthermore been attempted to diminish the adhesion of the bead to the crucible by making a crucible of a given material, such as platinum-gold and platinumgold-rhodium alloys. However, this could not completely obviate the drawback.
There has now been found a method in which said adhesion of the vitreous body to the crucible does not occur or is obviated, a bead being obtained, in which local stresses are reduced.
This is highly important for permitting automatic X- ray fluorescence analysis, which would otherwise not be feasible.
It has been found that the adhesion of the vitreous body to the crucible can be obviated by passing electric current through the areas of adhesion from the body towards the crucible.
The invention relates to a method of producing samples for analysis, in which a mixture of the substance to be tested and a substance, from which a vitreous body is formed by melting and subsequent cooling, is heated in or on a holder of electrically conductive material until the mixture is melted, after which it is cooled, and is characterized in that during the cooling of the vitreous body electric current is passed through the body towards the holder until the vitreous body no longer adheres to the holder.
The current may be passed through the vitreous body towards the holder in various ways. The holder may be connected to the negative terminal of a direct-voltage source, while an electrode, for example, of graphite wool, connected to the positive terminal, is pressed against the vitreous body. It has been found that the desired effect may furthermore be obtained by means of alternating current. In the interface between the vitreous body and the holder a blocking effect is produced so that, when alternating voltage is used, current is passed only in one direction, i.e. from the body to the holder.
The voltage to be used for the passage of current depends to some extent upon the material used for the vitreous body. It depends more intimately upon the temperature of said body at which the current starts passing through, owing to the intimate relationship between its resistance and temperature. It is advantageous to start the passage of current at a temperature at which the vitreous body is still viscous; with the frequently employed borax bead this is at about 600 C. to 700 C. In this case a voltage of 110 to 220 v. is suitable.
It has been found that the current can be advantageously passed through the vitreous body to the holder by means of spark discharge or voltage flash-over.
The spark discharge or the voltage flash-over may be achieved in known manner, for example, by holding a pointed electrode, connected to a voltage source of, for example, 50 kv., at a given distance, for example, 2 ems. above the vitreous body and by connecting the crucible to earth. The voltage flash-over has to take place through the bead towards the crucible. If the spark discharge is produced by direct voltage, the electrode above the vitreous body has to be connected to the positive terminal of the voltage source. It has been found that the spark discharge may also be produced by means. of alternating voltage. Due to the blocking effect in the interface between the vitreous body and the crucible the flash-over is also in this case produced only in one direction. The process of the disengagement of the vitreous body during the spark discharge can be observed visually and it can be assessed when the process has finished. It can thus be ascertained in a simple manner when the spark discharge can be finished.
It is advantageous to start the spark discharge, when the resistance of the vitreous body is still fairly low; this is the case, when the vitreous body is still at a higher temperature. Therefore, it is preferred to start the spark discharge when the vitreous body is still viscous. If borax is used, this is at 600 C. to 700 C. The discharge may be terminated, for example, at about 200 C. The spark discharge may also be started at a lower temperature than about 700 C. These values are not very critical. Also for this reason the method according to the invention contributes to the possibility of carrying out the X-ray fluorescence analysis automatically. Automation of the X-ray fluorescence analysis is essential for many industries, inter alia for the cement industry, in connection with the fact that frequently a very great number of samples has to be examined within a short period of time.
The holder is usually a crucible of conventional material, such as platinum, platinum-gold and graphite (electro-graphite, pyrolytic graphite). The substance forming, subsequent to melting and cooling, a vitreous body may be a known substance, for example, an alkali-tetra-borate, for instance borax, a phosphate and a bisulphate.
The method according to the invention will be explained with reference to the following examples.
(1) 4 parts by weight of borax were mixed with 1 part by weight of lime and stone (the substance to be tested). The mixture was melted in a crucible of platinum-gold (-5) by heating at about 1000 C. After the mass had completely melted, it was cooled in air. Above the melt was arranged a pointed electrode, connected to an alternating-voltage source of 50 kv., so that the distance between the electrode and the surface of the melt was about 2 ems. The crucible was connected to earth. The spark discharge was started at a temperature of about 700 C. of the vitreous body formed from the melt; during cooling the discharge was continued until the vitreous body had completely disengaged from the wall of the crucible. This took about 3 minutes.
(2) As described under (1), 4 parts by weight of sodium phosphate and 1 part by weight of cement were used to make a sample for analysis in a graphite crucible. The spark discharge was obtained by means of a direct-voltage source. The crucible was connected to the negative terminal.
(3) As described under (1), 4 parts by weight of borax and 1 part by weight of lime sand stone were used for preparing a sample for analysis in a platinum crucible. An electrode of graphite wool, connected to the positive terminal of a direct-voltage source of 220 v. was pressed against the surface of the sample which had become viscous when cooled to about 650 C. The crucible was connected to the negative terminal. The current was passed through during the cooling of the sample until it had disengaged from the crucible. This occurred when the temperature of the sample (the vitreous body) was about 250 C.
The method can be improved in that during the spark discharge the latter is surrounded by a stream of a gas, for example air. The direction of the stream should be from the electrode to the holder of the sample. This intprovement effects that the glass bead is disengaged from the holder in a shorter period of time. In many examples the disengagement of the sample was effected within 30 seconds.
What is claimed is:
1. A method of producing samples for X-ray fluorescence analysis comprising the steps of forming a mixture of a substance to be tested and a substance from which a vitreous body is formed by melting, heating said mixture while in contact with a holder of electrically conductive material until the mixture is melted, thereafter cooling the melted material to form a vitreous body, and passing an electric current through this body during cooling toward the holder until the vitreous body no longer adheres to the holder.
2. A method as claimed in claim 1, in which the current starts passing through before the vitreous body has completely solidified.
3. A method as claimed in claim 2, in which the electric current is passed through the body by means of spark discharge.
4. A method as claimed in claim 3, in which the spark discharge is surrounded by a streaming gas.
References Cited UNITED STATES PATENTS WILLIAM F. LINDQUIST, Primary Examiner
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL6609665A NL6609665A (en) | 1966-07-09 | 1966-07-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3546452A true US3546452A (en) | 1970-12-08 |
Family
ID=19797138
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US652027A Expired - Lifetime US3546452A (en) | 1966-07-09 | 1967-07-10 | Method of producing samples for x-ray fluorescence analysis |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US3546452A (en) |
| BE (1) | BE701086A (en) |
| CH (1) | CH487404A (en) |
| GB (1) | GB1191733A (en) |
| NL (1) | NL6609665A (en) |
| SE (1) | SE322072B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10361525B4 (en) * | 2003-12-23 | 2005-11-17 | Umicore Ag & Co. Kg | Process for the preparation of orodispersible tablets for the determination of the content of ceramic powders on platinum group metals by means of RFA |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2561818A (en) * | 1945-01-29 | 1951-07-24 | Saint Gobain | Electrolytic method of protecting the wall of a glass furnace |
| US2901629A (en) * | 1954-01-26 | 1959-08-25 | J J Maguire | Method and apparatus for slag detection in metal sheets |
-
1966
- 1966-07-09 NL NL6609665A patent/NL6609665A/xx unknown
-
1967
- 1967-06-28 SE SE9529/67*A patent/SE322072B/xx unknown
- 1967-07-06 CH CH960467A patent/CH487404A/en not_active IP Right Cessation
- 1967-07-06 GB GB31121/67A patent/GB1191733A/en not_active Expired
- 1967-07-07 BE BE701086D patent/BE701086A/xx unknown
- 1967-07-10 US US652027A patent/US3546452A/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2561818A (en) * | 1945-01-29 | 1951-07-24 | Saint Gobain | Electrolytic method of protecting the wall of a glass furnace |
| US2901629A (en) * | 1954-01-26 | 1959-08-25 | J J Maguire | Method and apparatus for slag detection in metal sheets |
Also Published As
| Publication number | Publication date |
|---|---|
| DE1648994B2 (en) | 1975-06-26 |
| CH487404A (en) | 1970-03-15 |
| BE701086A (en) | 1968-01-08 |
| SE322072B (en) | 1970-03-23 |
| DE1648994A1 (en) | 1971-08-26 |
| NL6609665A (en) | 1968-01-10 |
| GB1191733A (en) | 1970-05-13 |
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