JP3359576B2 - Decomposition method and analysis method for non-oxide sample - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decomposing a non-oxide sample used for chemical analysis of a non-oxide sample, and a method for analyzing the same.

[0002]

2. Description of the Related Art Conventionally, a method of decomposing a non-oxide sample by alkali melting and then dissolving the decomposed product for chemical analysis has been used in order to obtain a quantitative element value and an element composition ratio of the non-oxide sample. ing. When a non-oxide sample is decomposed by alkali melting, the non-oxide sample generally contains sodium carbonate, potassium carbonate, sodium carbonate and boric acid as fluxes,
A method of heating by adding potassium carbonate and any one of boric acid, lithium borate, and potassium sodium carbonate has been performed, and a method of preheating and oxidizing a non-oxide sample in an oxygen atmosphere (Japanese Patent Publication No. 63-43709). Publication) and a method of performing alkali melting by heating in an excess oxygen atmosphere and V
A method is known in which a small amount of an oxidizing aid such as ₂ O ₅ , KNO ₃ , and LiNO ₃ is added to carry out alkali melting (JP-A-62-144043).

At this time, when the non-oxide sample is a powder, it is necessary to carefully carry out alkali melting so that the non-oxide sample is not scattered by gradually raising the temperature and oxidizing it over a long period of time from a low temperature. Therefore, it takes a long time. For example, in the chemical analysis method of fine silicon carbide powder for fine ceramics (JISR 1616-1994),
Place the non-oxide sample in an electric furnace at 700 ° C. for 1 hour, 800 ° C. for 2 hours, and finally
Heating at 00 ° C. for 20 minutes was required.

Further, when the non-oxide sample is a sintered body, there is no official chemical analysis method such as JIS and the heat resistance is excellent, so that the non-oxide sample can be used under an oxygen atmosphere (Japanese Patent Publication No. 63-43709) or V _2. O _5, KNO _3, be LiNO ₃ adding an oxidizing aid such as (JP 62-144043 JP), 700
There was almost no change in heating at -800 ° C, and heating at a higher temperature was necessary. However, when heating is performed at a high temperature for a long time as described above, the oxidation reaction occurs extremely violently, so that alkali melting cannot be performed without scattering of the non-oxide sample. In addition, since the decomposed non-oxide sample reacts with the platinum tool to form an alloy, there is a problem that decomposition of the non-oxide sample is hindered. From the above, even if the decomposition product after alkali melting was dissolved and subjected to chemical analysis, it was not possible to accurately obtain the element quantitative value and the element composition ratio of the non-oxide sample.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such problems of the related art,
The purpose is to add a transition metal oxide to the non-oxide sample and flux so that the non-oxide sample can be gently melted while accelerating oxidation during alkali melting. Another object of the present invention is to provide a method for decomposing a non-oxide sample and a method for analyzing the non-oxide sample, which can rapidly decompose the non-oxide sample without scattering of the non-oxide sample during alkali melting.

[0006]

That SUMMARY OF THE INVENTION According to the present invention, the non-oxide sample to a disassembly method of decomposing an alkali fusion method, the non-oxide sample and flux, iron oxides, black
A non-oxide material characterized by performing a mild melting reaction while accelerating oxidation of the non-oxide sample during alkali melting by adding a transition metal oxide composed of a metal oxide or a combination thereof. A method for decomposing a sample is provided. Further, according to the present invention, by decomposing the non-oxide samples alkali fusion method, an analytical method for analyzing non-oxide sample, the non-oxide sample and flux, iron acid
By adding a transition metal oxide consisting of an oxide of chromium or chromium or a combination thereof, it is possible to promote a gentle melting reaction while accelerating oxidation of the non-oxide sample during alkali melting. A method for analyzing a non-oxide sample is provided.

[0007]

In the present invention, the non-oxide sample is made of a carbide, a nitride, a boron compound, or a mixture or a compound thereof, and may be any of a raw material powder, a prepared powder, a calcined body, and a sintered body. Is preferable. Among the above, the non-oxide sample is more preferably BN, B ₄ C, SiC, or Si ₃ N ₄ .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The decomposition method and the analysis method of the present invention include the steps of:
By adding an oxide of a transition metal composed of a compound or a combination thereof, the melting reaction is gently performed while promoting oxidation of the non-oxide sample during alkali melting. Thus, the non-oxide sample can be quickly decomposed without scattering of the non-oxide sample during alkali melting. Further, by dissolving the decomposed product and performing chemical analysis, it is possible to accurately obtain the element quantitative value and the element composition ratio of the non-oxide sample which are important in the material characteristics.

The main feature of the decomposition and analysis method of the present invention is to add a transition metal oxide or an oxide that becomes a transition metal oxide upon alkali melting to a non-oxide sample and a flux. This is because the transition metal oxide acts on the non-oxide sample to accelerate the decomposition reaction with the flux, and at the same time, the oxygen in the transition metal oxide promotes the oxidation of the non-oxide sample. Therefore, it is presumed that the melting reaction can be performed gently while promoting oxidation during alkali melting.

At this time, the amount of the transition metal oxide to be added is preferably 1 to 160% by weight of the non-oxide sample. This is because if the added amount of the transition metal oxide is less than 1% by weight, the above effects cannot be exhibited. On the other hand, when the added amount of the oxide of the transition metal is 160
If the content is more than 10% by weight, the oxide of the transition metal is adsorbed on the platinum dish used at the time of alkali melting.

Further, according to the decomposition method and the analysis method of the present invention, after adding and mixing a transition metal oxide and a flux to a non-oxide sample to be decomposed, heating is performed in a burner or an electric furnace (700 to 1100). ° C), and decompose the non-oxide sample by alkali melting. At this time, the non-oxide sample to be decomposed is preferably crushed to 3 mm or less in order to increase the decomposition speed.

The oxide of the transition metal used in the present invention is not particularly limited, but is preferably composed of an oxide of iron, an oxide of chromium, or a combination thereof. Further, as these oxides, for example, in the case of iron oxide, Fe
_{Like 2} (CO ₃ ) ₃ , it includes those which form an iron oxide upon alkali melting, such as carbonates and oxalates of Fe.

The non-oxide sample applicable in the present invention is not particularly limited, and may be any of a raw material powder, a compounded powder, a calcined body, and a sintered body made of carbide, nitride, boron compound, or a mixture or compound thereof. The method can be applied to a sample containing silicon carbide, silicon nitride, or boron carbide. Of the above-mentioned samples, more specifically, BN, B ₄ C, SiC, or Si ₃ N ₄ can be more preferably applied.

As the flux used in the present invention, those conventionally used in a melting method can be used.
Sodium carbonate, potassium carbonate, sodium carbonate and boric acid, potassium carbonate and boric acid, lithium borate, sodium potassium carbonate, sodium hydroxide, potassium hydroxide or a mixture thereof can be suitably used.

[0016]

EXAMPLES Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto. In addition, the method of quantifying the total silicon in the non-oxide sample obtained in each example is based on the coagulation weight absorption spectrophotometry method (JIS R1616-1994, JIS
R1603-1994). Here, the principle of the coagulation weight absorption spectroscopy method is that the sample is melted with sodium carbonate and boric acid, polyethylene oxide is added, silica is coagulated and filtered, the precipitate is ignited, weighed, and hydrofluoric acid is added. After volatilizing silicon dioxide by heating and measuring again, the amount of main silicon dioxide was determined from the weight loss, the filtrate was separated, and the amount of dissolved silicon dioxide was determined by molybdenum blue absorption spectrophotometry. The total silicon content is calculated from the sum of

Example 1 0.25 g of a sintered silicon carbide sample crushed to 3 mm or less was placed on a platinum dish, and 0.1 g of iron oxide, 2.6 g of sodium carbonate and 0.4 g of boric acid were prepared.
And melted in an electric furnace (700-1100 ° C.) to decompose. Hydrochloric acid was added to the obtained decomposed product,
The total amount of silicon was determined in the same manner as in the IS R1616-1994 method. Table 1 shows the results of the total silicon analysis.

(Comparative Example 1) 0.25 g of a sintered silicon carbide sample crushed to 3 mm or less was placed in a platinum dish, 2.6 g of sodium carbonate and 0.4 g of boric acid were added and mixed, and the mixture was placed in an electric furnace. 700 ° C for 1 hour, 800 ° C for 2 hours, 10
It was melted and decomposed by heating at 00 ° C for 20 minutes and finally at 1100 ° C for 10 minutes. Hydrochloric acid was added to the obtained decomposed product, and the total amount of silicon was determined in the same manner as in JIS R1616-1994. Table 1 shows the results of the total silicon analysis.

Comparative Example 2 0.25 g of a sintered silicon carbide sample crushed to 3 mm or less was placed on a platinum dish, and 0.1 g of iron oxide, 2.6 g of sodium carbonate, and 0.4 g of boric acid were prepared.
Was added and mixed, and the mixture was melted and decomposed by a burner while supplying oxygen gas from the upper portion of a platinum dish as an alkali decomposition vessel. Hydrochloric acid was added to the obtained decomposed product, and the product was subjected to JIS R16
The total amount of silicon was determined in the same manner as in the 16-1994 method. Table 1 shows the results of the total silicon analysis.

Comparative Example 3 0.25 g of a sintered silicon carbide sample crushed to 3 mm or less was placed on a platinum dish, and 2.6 g of sodium carbonate, 0.4 g of boric acid, and L as an oxidation aid were used.
Add iNO ₃ and mix, place in electric furnace at 700 ° C. for 1
Melting / decomposition was performed by heating at 800 ° C. for 2 hours, at 1000 ° C. for 20 minutes, and finally at 1100 ° C. for 10 minutes. Hydrochloric acid was added to the obtained decomposed product, and JIS R
The total amount of silicon was determined in the same manner as in the 1616-1994 method. Table 1 shows the results of the total silicon analysis.

Comparative Example 4 0.25 g of a sintered silicon carbide sample crushed to 3 mm or less was placed in a platinum dish, heated to 800 to 1000 ° C. while supplying oxygen gas, and then 2.6 g of sodium carbonate was added. Add and mix 0.4 g of boric acid, place in an electric furnace at 700 ° C. for 1 hour, 800 ° C. for 2 hours,
It was melted and decomposed by heating at 000 ° C for 20 minutes and finally at 1100 ° C for 10 minutes. Hydrochloric acid was added to the obtained decomposed product, and the total amount of silicon was determined in the same manner as in JIS R1616-1994.

[0022]

[Table 1]

(Consideration: Example 1, Comparative Examples 1 to 4) In Example 1, when an appropriate amount of iron oxide is added, when the sample is alkali-melted, the oxidation reaction proceeds gently, so that the sample is scattered. Could be disassembled without any problems. At this time, the total silicon quantitative value in silicon carbide was calculated as: 70.
Compared with 04 wt%, it was almost equal to 70.06 wt%, and it was confirmed that the sample was not scattered and was completely decomposed.

On the other hand, in Comparative Example 1, since the sample was excellent in heat resistance even when the sample was alkali-melted,
The heating at 0 ° C. hardly changed, and heating at a higher temperature was required. As a result, it was found that the oxidation reaction was extremely violent and it was difficult to melt the alkali without scattering of the sample, so that the total silicon quantitative value was low and the variation was large. As in Comparative Example 4, after the sample was preheated in an oxygen atmosphere, alkali melting was performed in the same manner as in Comparative Example 1, and the same results as in Comparative Example 1 were obtained. Also,
In Comparative Example 2, even when the sample was alkali-melted under the supply of oxygen gas, the sample was excellent in heat resistance.
There was almost no change in heating, and heating at a higher temperature was necessary. Because of this, the oxidation reaction is very violent, and it is difficult to melt the alkali without scattering the sample.
It was found that the total silicon quantitative value was low and the variation was large. Further, Comparative Example 3 shows that the oxidation aid Li
Even if the sample is alkali-melted by adding NO ₃ , the sample is excellent in heat resistance, so that there is almost no change by heating at 700 to 800 ° C., and heating at a higher temperature is required.
As a result, it was found that the oxidation reaction was extremely violent and it was difficult to melt the alkali without scattering of the sample, so that the total silicon quantitative value was low and the variation was large. Similar results were obtained when V ₂ O ₅ or KNO ₃ was used as the oxidation aid. From the above, in Comparative Examples 1 to 4, the quantitative value of total silicon in silicon carbide was calculated as: 70.
68.98-69.28 wt% compared to 04 wt%
It was found that not only a low value, but also a large variation in measured values.

(Examples 2 to 8, Comparative Examples 5 to 6) 3 mm
0.25 g of the sintered silicon carbide sintered body sample was placed on a platinum dish, and iron oxide was added to 2.6 g of sodium carbonate and 0.4 g of boric acid as shown in Table 2 and mixed.
0 to 1100 ° C) and decomposed. At this time, each melting state is shown in Table 2.

[0026]

[Table 2]

(Discussion: Examples 2 to 8, Comparative Examples 5 to 6)
It was found that when the addition amount of iron oxide was 1 mg with respect to 0.25 g of the silicon carbide sintered body sample, a small flame due to oxidation was raised and the sample was scattered (Comparative Example 5). In addition, when the added amount of iron oxide was 500 mg, it was found that the decomposed sample reacted with the platinum device to form an alloy, and iron was considerably adsorbed on the platinum dish (Comparative Example 6). on the other hand,
When the amount of iron oxide added is in the range of 2.5 to 400 mg (1 to 160% by weight based on silicon carbide), there is little or no flame due to oxidation, and silicon carbide can be gently melted and decomposed. Was confirmed (Examples 2 to 8).

(Example 9, Comparative Example 7) 0.25 g of a silicon carbide powder sample was placed on a platinum dish, and 0.1 g of chromium oxide was added.
2.6 g of sodium carbonate and 0.4 g of boric acid were added and mixed, melted and decomposed in an electric furnace (700 to 1100 ° C.) (Example 9). In addition, silicon carbide powder sample 0.25
g in a platinum dish, 2.6 g of sodium carbonate and 0.4 g of boric acid were added and mixed, and put in an electric furnace at 700 ° C. for 1 hour.
By heating at 800 ° C. for 2 hours and finally at 1000 ° C. for 20 minutes, it was melted and decomposed (Comparative Example 7).

(Consideration: Example 9, Comparative Example 7) Comparative Example 7
Then, it takes 3 hours and 30 minutes or more to decompose the silicon carbide powder. In Example 9, however, by adding an appropriate amount of chromium oxide, when the sample is alkali-melted, the oxidation reaction proceeds gently. By heating for about 30 minutes (1/7 or less of the decomposition time of Comparative Example 7), the sample could be decomposed without being scattered.

(Example 10, Comparative Example 8) 0.25 g of a silicon nitride sintered body sample crushed to 3 mm or less was placed on a platinum dish, and 0.1 g of chromium oxide and 2.
6 g and 0.4 g of boric acid were added and mixed.
0-1100 ° C.) to decompose (Example 1)
0). Also, 0.25 g of a silicon nitride sintered body sample crushed to 3 mm or less was placed on a platinum dish, and 2.6 g of sodium carbonate was placed.
And 0.4 g of boric acid were added and mixed. First, the mixture was heated at a low temperature, and finally heated and melted and decomposed at 1000 ° C. or higher (Comparative Example 8).

(Consideration: Example 10, Comparative Example 8) In Example 10, the addition of a suitable amount of chromium oxide allows the oxidation reaction to proceed gently when the sample is alkali-melted, so that the sample is not scattered. Could be disassembled.
On the other hand, in Comparative Example 8, the sample violently oxidized from about 500 ° C., and the alkali could not be melted without scattering of the sample.

(Example 11, Comparative Example 9) 0.25 g of a boron carbide powder sample was placed on a platinum dish, and 0.1 g of iron oxide, 2.6 g of sodium carbonate and 0.4 g of boric acid were added and mixed. (700-1100 ° C.) and melted and decomposed (Example 11). In addition, boron carbide powder sample 0.25
g was placed in a platinum dish, and 2.6 g of sodium carbonate and 0.4 g of boric acid were added and mixed. First, the mixture was heated at a low temperature, and finally melted and decomposed by heating at 1000 ° C. or higher (Comparative Example 9).

(Consideration: Example 11, Comparative Example 9) In Example 11, the addition of an appropriate amount of iron oxide allows the oxidation reaction to proceed gently when the sample is alkali-melted.
By heating for about 30 minutes (1/7 or less of the decomposition time according to JIS R1616-1994 method), the sample could be decomposed without scattering. On the other hand, in Comparative Example 9, the sample was 50
Violent oxidation reaction occurred from about 0 ° C., and alkali melting could not be performed without scattering of the sample.

[0034]

As described above, according to the present invention, a non-oxide sample can be rapidly decomposed without scattering of the non-oxide sample during alkali melting. Further, by dissolving the decomposed product and performing chemical analysis, it is possible to accurately obtain the element quantitative value and the element composition ratio of the non-oxide sample which are important in the material characteristics.

Claims (6)

(57) [Claims] 1. A decomposition method for decomposing a non-oxide sample by an alkali melting method, wherein iron oxide and chromium oxide are added to the non-oxide sample and the flux.
Alternatively , by adding an oxide of a transition metal composed of these combinations , the decomposition of the non-oxide sample is characterized by performing a gentle melting reaction while accelerating the oxidation of the non-oxide sample during alkali melting. Method. 2. The method for decomposing a non-oxide sample according to claim 1, wherein the non-oxide sample comprises a carbide, nitride, boron compound, or a mixture or compound thereof. 3. The non-oxide sample is BN, B ₄ C, Si
2. The method for decomposing a non-oxide sample according to claim 1, wherein the non-oxide sample is C or Si ₃ N ₄ . 4. The method according to claim 1, wherein the non-oxide sample is a raw material powder, a prepared powder,
The method for decomposing a non-oxide sample according to any one of claims 1 to 3 , wherein the method is a calcined body or a sintered body. 5. An analysis method for analyzing a non-oxide sample by decomposing the non-oxide sample by an alkali melting method, wherein the non-oxide sample and the flux include an oxide of iron and an oxide of chromium. Ah
Alternatively , by adding a transition metal oxide composed of these combinations , the non-oxide sample is characterized in that the melting reaction is carried out gently while promoting the oxidation during alkali melting of the non-oxide sample. Method. 6. The method for analyzing a non-oxide sample according to claim 5 , wherein the non-oxide sample comprises a carbide, a nitride, a boron compound, or a mixture or compound thereof.