Preparation of inorganic samples by fusion
In a process for the preparation of inorganic sample disks for analysis, the sample, in powdered form, is mixed with a powdered reagent flux which has been pre-melted. In an inert gas atmosphere, the mixture is placed in a graphite crucible and heated to a temperature slightly above 1000° C. After the flux dissolves the sample, a homogenous mix is produced. This mix is then poured into a graphite mold, the bottom of which contains a molten pool of an inert metal, such as gold, which acts as a smooth receiving surface. Upon cooling, the material in the mold solidifies, resulting in a glassy disk that can be analyzed. Cooling can be accelerated by making use of a cooling fluid that has a substantially higher thermal capacity than air.
1. A process for the manufacture of sample disks from a powdered inorganic sample, comprising the steps of:
combining a powdered reagent with the sample in a crucible;
heating the crucible to obtain a mix in which the sample is dissolved;
pouring the mix into a mold containing a molten metal as a receiving bottom surface for the mix, the molten metal being denser than the mix, being substantially inert to the mix and not adherent thereto and having a melting point below 1200° C.; and
cooling the mix while in the mold in order to form a disk.
2. The process of claim 1 performed with a mold having an inner bottom wall and an inner periphery which is undercut in the vicinity of the bottom wall so that the interior of the mold has an increased lateral dimension in the vicinity of the bottom wall.
3. The process of claim 1 wherein the metal is gold or a gold alloy.
4. The process of claim 3 wherein the reagent is melted prior to the combining step.
5. The process of claim 4 wherein the cooling step includes introducing a fluid that has a substantially higher thermal capacity than air.
6. The process of claim 5 wherein the fluid is one of water or liquefied which is depressurized upon introduction.
7. The process of claim 5 wherein the crucible and mold are made of graphite, the process being performed in an atmosphere consisting essentially of an inert gas.
8. The process of claim 7 wherein the inert gas is a member of the noble gases group.
9. The process of claim 1 wherein the reagent is melted prior to the combining step.
10. The process of claim 1 wherein the cooling step includes introducing a fluid that has a substantially higher thermal capacity than air.
11. The process of claim 1 wherein the crucible and mold are made of graphite, the process being performed in an atmosphere consisting essentially of an inert gas.
12. The process of claim 11 wherein the inert gas includes a member of the group containing nitrogen, argon, and neon.
13. A process for the manufacture of sample disks from a powdered inorganic sample, comprising the steps of:
combining a melted, powdered reagent with the sample in a crucible;
heating the crucible to obtain a mix in which the sample is dissolved;
pouring the mix into a mold containing a molten metal as a receiving bottom surface for the mix; and
cooling the mix while in the mold in order to form a disk.
14. The process of claim 13 wherein the cooling step includes introducing a fluid that has a substantially higher thermal capacity than air.
15. The process of claim 14 wherein the fluid is one of water and liquefied which is depressurized upon introduction.
16. The process of claim 14 wherein the crucible and mold are made of graphite, the process being performed in an atmosphere consisting essentially of an inert gas.
17. The process of claim 16 wherein the inert gas includes a member of the group containing nitrogen, argon, and neon.
18. The process of claim 13 wherein the crucible and mold are made of graphite, the process being performed in an atmosphere consisting essentially of an inert gas.
19. The process of claim 18 wherein the inert gas includes a member of the group containing nitrogen, argon, and neon.
20. A process for the manufacture of sample disks from a powdered inorganic sample, comprising the steps of:
combining a powdered reagent with the sample in a crucible;
heating the crucible to obtain a mix in which the sample is dissolved;
pouring the mix into a mold containing a molten metal as a receiving bottom surface for the mix; and
cooling the mix while in the mold by introducing a fluid that has a substantially higher thermal capacity than air, thereby forming a disk.
21. The process of claim 20 wherein the fluid is one of water and liquefied which is depressurized upon introduction.
22. The process of claim 20 wherein the reagent is melted prior to the combining step.
23. The process of claim 20 wherein the crucible and mold are made of graphite, the process being performed in an atmosphere consisting essentially of an inert gas.
24. The process of claim 23 wherein the inert gas includes a member of the group containing nitrogen, argon, and neon.
25. A process for the manufacture of sample disks from a powdered inorganic sample, comprising the steps of:
combining a powdered reagent with the sample in a crucible made of graphite;
heating the crucible to obtain a mix in which the sample is dissolved;
pouring the mix into a mold made of graphite, the mold containing a molten metal as a receiving bottom surface for the mix; and
cooling the mix while in the mold in order to form a disk;
the process being performed in an atmosphere consisting essentially of an inert gas and the mold having its bottom coated with a metal.
26. The process of claim 25 wherein the inert gas includes a member of the group containing nitrogen, argon, and neon.
27. The process of claim 25 wherein the reagent is melted prior to the combining step.
28. The process of claim 25 wherein the cooling step includes introducing a fluid that has a substantially higher thermal capacity than air.