CN111122373B - Method for testing silicon content in nano silicon-based material - Google Patents
Method for testing silicon content in nano silicon-based material Download PDFInfo
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- CN111122373B CN111122373B CN201811279362.3A CN201811279362A CN111122373B CN 111122373 B CN111122373 B CN 111122373B CN 201811279362 A CN201811279362 A CN 201811279362A CN 111122373 B CN111122373 B CN 111122373B
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- 239000000463 material Substances 0.000 title claims abstract description 111
- 239000005543 nano-size silicon particle Substances 0.000 title claims abstract description 109
- 238000000034 method Methods 0.000 title claims abstract description 82
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 79
- 239000010703 silicon Substances 0.000 title claims abstract description 78
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 77
- 238000012360 testing method Methods 0.000 title claims abstract description 55
- 238000010438 heat treatment Methods 0.000 claims abstract description 78
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 72
- 238000010304 firing Methods 0.000 claims abstract description 49
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 31
- 238000001816 cooling Methods 0.000 claims abstract description 27
- 238000010998 test method Methods 0.000 claims abstract description 27
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 24
- 238000001914 filtration Methods 0.000 claims abstract description 21
- 230000001590 oxidative effect Effects 0.000 claims abstract description 20
- 238000002474 experimental method Methods 0.000 claims abstract description 18
- 238000005303 weighing Methods 0.000 claims abstract description 15
- 230000004584 weight gain Effects 0.000 claims abstract description 14
- 235000019786 weight gain Nutrition 0.000 claims abstract description 14
- 239000002253 acid Substances 0.000 claims abstract description 10
- 239000007787 solid Substances 0.000 claims abstract description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 22
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 13
- 229910052760 oxygen Inorganic materials 0.000 claims description 13
- 239000001301 oxygen Substances 0.000 claims description 13
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 12
- -1 polytetrafluoroethylene Polymers 0.000 claims description 11
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 11
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 239000002131 composite material Substances 0.000 claims description 9
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 8
- 239000010425 asbestos Substances 0.000 claims description 8
- 229910017604 nitric acid Inorganic materials 0.000 claims description 8
- 229910052895 riebeckite Inorganic materials 0.000 claims description 8
- 238000009835 boiling Methods 0.000 claims description 7
- 239000011164 primary particle Substances 0.000 claims description 7
- 239000007791 liquid phase Substances 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 5
- 238000001514 detection method Methods 0.000 abstract description 8
- 239000000047 product Substances 0.000 description 34
- 238000004321 preservation Methods 0.000 description 19
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 18
- 229910052593 corundum Inorganic materials 0.000 description 16
- 239000010431 corundum Substances 0.000 description 16
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 description 16
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 8
- 239000003153 chemical reaction reagent Substances 0.000 description 7
- 230000018044 dehydration Effects 0.000 description 7
- 238000006297 dehydration reaction Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 6
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 5
- 239000003513 alkali Substances 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000011521 glass Substances 0.000 description 5
- 229910052906 cristobalite Inorganic materials 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 239000002210 silicon-based material Substances 0.000 description 4
- 229910052905 tridymite Inorganic materials 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000010306 acid treatment Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 230000020477 pH reduction Effects 0.000 description 3
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 description 3
- 239000011856 silicon-based particle Substances 0.000 description 3
- 239000002153 silicon-carbon composite material Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- 229910000882 Ca alloy Inorganic materials 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- OSMSIOKMMFKNIL-UHFFFAOYSA-N calcium;silicon Chemical compound [Ca]=[Si] OSMSIOKMMFKNIL-UHFFFAOYSA-N 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 238000005485 electric heating Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000011572 manganese Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical class [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000004380 ashing Methods 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009614 chemical analysis method Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- HXOLFXRMWWHLMH-UHFFFAOYSA-L disodium boric acid carbonate Chemical compound [Na+].[Na+].OB(O)O.[O-]C([O-])=O HXOLFXRMWWHLMH-UHFFFAOYSA-L 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000011863 silicon-based powder Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/44—Sample treatment involving radiation, e.g. heat
Abstract
The invention provides a method for testing the silicon content in a nano silicon-based material, which comprises the following steps: 1) Weighing a nano silicon-based material sample, placing the sample in a container, heating the sample by using acid, filtering the sample by using filter paper, and transferring the solid to the filter paper to obtain filter residues; 2) Transferring the filter paper and filter residues into a heat-resistant container, heating until the filter paper is carbonized, and cooling the heat-resistant container; 3) Burning the heat-resistant container and the heating product in an oxidizing atmosphere to completely convert the nano silicon-based material sample into silicon dioxide; 4) After cooling the heat-resistant container and the firing product, weighing to obtain the total weight of the heat-resistant container and the firing product; 5) A blank experiment is carried out in the whole process without using a nano silicon-based material sample, so that the weight gain of the heat-resistant container for the blank experiment is obtained; 6) And calculating the silicon content in the nano silicon-based material sample. The test method provided by the invention has the advantages of accurate detection, high precision, simple and convenient operation and wide detection range.
Description
Technical Field
The invention belongs to the technical field of measurement and test, relates to a method for testing silicon content, and particularly relates to a method for testing the silicon content in a nano silicon-based material.
Background
The nano silicon-based material refers to: nano silicon/nano silicon oxide material or composite material of nano silicon/nano silicon oxide material and carbon material which can volatilize or react at high temperature to generate gas.
The silicon-carbon composite material and the silicon oxide material for the lithium ion secondary battery are typical representatives of the nano silicon-based materials, and the silicon content of the silicon-carbon composite material and the silicon oxide material has a remarkable influence on the material performance and is one of indexes mainly focused by downstream users (battery manufacturers). At present, most of documents and standards related to silicon content tests at home and abroad adopt acid-base dissolution treatment, such as removal of silicon by hydrofluoric acid or melting of alkali to convert into silicate, acidification and dehydration by perchloric acid to generate insoluble silicic acid, filtration, high-temperature burning and dehydration to generate silicon dioxide, weighing and calculation, and the detection process is complex and difficult to control, and has poor accuracy and repeatability.
For example, CN 105388084B discloses a method for detecting the silicon content in manganese-rich slag, wherein a manganese-rich slag sample is crushed to a granularity less than or equal to 0.125mm and dried; melting with sodium carbonate-boric acid at 890-910 ℃, transferring into a beaker with hydrochloric acid, dehydrating with perchloric acid, filtering, and washing; burning at 1050-1150 deg.c to constant weight and calculating to obtain Si content.
CN 102213704A discloses a method for determining the content of silicon and calcium elements in a silicon-calcium alloy, wherein a silicon-calcium alloy sample is melted in a nickel crucible at high temperature by sodium hydroxide solid; transferring deionized water and hydrochloric acid into an evaporation dish, baking, and adding hydrochloric acid and water to dissolve salts; filtering with quantitative filter paper while the mixture is hot; the filtrate is used for testing the content of calcium by a capacity method, and filter residues and filter papers are ashed and burned together until the weight is constant; then adding hydrofluoric acid and sulfuric acid to convert silicon dioxide into silicon tetrafluoride gas, removing, filtering, ashing filter residues and filter paper together, and burning to constant weight; the weight difference of the constant weight before and after the treatment with hydrofluoric acid is used for obtaining the weight of the silicon dioxide, and then the silicon content in the sample is obtained through calculation.
GB/T223.60-1997 specifies a method for measuring silicon content by a chemical analysis method of steel and alloy, namely a method for measuring silicon content by a perchloric acid dehydration gravimetric method, wherein steel and alloy samples are dissolved by hydrochloric acid and nitric acid, and are dehydrated by perchloric acid to generate insoluble silicic acid, and the insoluble silicic acid is filtered and washed, and then burned and dehydrated to generate silicon dioxide. Treating with sulfuric acid and hydrofluoric acid to volatilize and remove silicon to obtain silicon tetrafluoride. The silicon content was calculated from the weight difference weighed before and after the silicon removal.
The method adopts the testing principle that silicate is obtained by alkali melting or acid treatment, perchloric acid is dehydrated to generate insoluble silicic acid, and the water loss is burnt to generate silicon dioxide; most methods also use hydrofluoric acid treatment to volatilize and remove silicon in the form of silicon tetrafluoride gas, then burn the silicon dioxide to obtain the silicon content in the sample by determining the weight of the silicon dioxide through the weight difference of the constant weight before and after the hydrofluoric acid treatment. This is because, when elemental silicon reacts with oxygen at high temperature, a dense silica protective film is easily formed on the surface, thereby preventing further reaction, so that it is not possible to completely convert elemental silicon into silica under normal conditions. The simple substance silicon powder can be completely converted into silicate at high temperature after being mixed with alkali flux, and can be converted into silicon dioxide through the steps of acidification, dehydration, filtration and burning, thereby realizing the determination of silicon content. So the weight method used at present is used for testing the silicon content by taking the principle as the detection basis.
The existing weight method for detecting the silicon content adopts the principle that the simple substance silicon and alkali are melted and reacted to generate silicate, and then the silicate is converted into silicon dioxide through the steps of acidification, dehydration, filtration and burning. The operation steps are long, and the types and the quantity of the strong acid and alkali reagents which are needed to be used are various, including high-risk reagents such as perchloric acid, hydrofluoric acid and the like; and the method has the advantages of more pollution introduced in the operation process, high operation difficulty and low efficiency due to more reagents and long operation steps; for samples with higher silicon content, the amount of insoluble silicic acid generated in the reaction process is large, so that the steps of dehydration, filtration and the like are difficult to execute; particularly, for the nano silicon-based material, due to small granularity, the generated insoluble silicic acid particles are small and are easy to block filter paper holes, so that the operation difficulty is further increased, the recovery rate is low, and the repeatability of a test result is poor.
The nanometer silicon-based material is a material which is newly appeared in recent years, and has the biggest characteristic that the primary particle size of silicon/silicon oxide in the material is nanometer size, and a great deal of researches on the nanometer material show that the nanometer material has a plurality of special physical and chemical properties compared with the common material. The practical operation finds that when the silicon content in the nano silicon-based material is tested by referring to the existing silicon content testing method, the steps of dehydration, filtration and the like are very difficult to implement, the testing time is long, the efficiency is low, and even a repeatable testing result cannot be obtained.
Therefore, developing a test method suitable for the silicon content in the nano silicon-based material is a technical problem in the current measurement and test technical field.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a method for testing the silicon content in a nano silicon-based material. The testing method provided by the invention adopts a firing weight method to accurately and efficiently determine the silicon content in the nano silicon-based material.
In order to achieve the above purpose, the invention adopts the following scheme:
the invention provides a method for testing the silicon content in a nano silicon-based material, which comprises the following steps:
(1) Weighing a nano silicon-based material sample, placing the sample in a container, heating the sample by using acid, filtering the sample by using filter paper, and transferring the solid to the filter paper to obtain filter residues;
(2) Transferring the filter paper and filter residues in the step (1) into a heat-resistant container, heating the filter paper until the filter paper is carbonized to obtain a heated product, and then cooling the heat-resistant container;
(3) Firing the heat-resistant container in the step (2) and a heating product in an oxidizing atmosphere, and completely converting the nano silicon-based material sample into silicon dioxide to obtain a firing product;
(4) Cooling the heat-resistant container and the firing product in the step (2), and weighing to obtain the total weight of the heat-resistant container and the firing product;
(5) A blank experiment is carried out in the whole process according to the method of the previous step without using a nano silicon-based material sample, so that the weight gain of the blank experiment heat-resistant container is obtained;
(6) The silicon content in the nano silicon-based material sample is calculated according to the following formula:
wherein Si% is the silicon content in the nano silicon-based material sample, and the weight percent is the silicon content in the nano silicon-based material sample;
m 2 the unit is the total weight of the heat-resistant container and the burning product: g;
m 1 the weight of the heat-resistant container is as follows: g;
m 0 weight gain of the heat-resistant container for blank experiments, unit: g;
m is the weight of the nano silicon-based material sample, and the unit is: g.
the testing method provided by the invention utilizes the special property of the nano silicon-based material, wherein the silicon particle size in the nano silicon-based material is nano-scale, has different properties from those of the silicon material with the conventional particle size, and can not form a complete silicon dioxide protective film on the surface when the silicon particle size is subjected to oxidation reaction with oxygen at high temperature, so that the reaction can be continuously carried out until the silicon particle size is completely oxidized into silicon dioxide.
In the test method provided by the invention, the blank experiment in the step (5) is performed completely according to the methods of the step (1), the step (2), the step (3) and the step (4) except that the nano silicon-based material sample is not used (namely, the blank experiment is performed in the whole process), which is equivalent to the operation of the step (1) to the step (4) on the filter paper in the step (1), and the weight gain of the heat-resistant container in the blank experiment is the weight of ash left after the filter paper is burnt. And (5) the filter paper used in the blank experiment in the step (5) is the same as the filter paper used in the step (1) in material and size.
In the test method provided by the invention, 0.4675 in the formula of the step (6) is the mass fraction of silicon element in silicon dioxide.
The testing method provided by the invention can accurately and efficiently determine the silicon content in the nano silicon-based material.
In the test method provided by the invention, the nano silicon-based material not only comprises a silicon-based material with a nano-scale size, but also comprises equivalent nano silicon-based materials with a micro-scale size. For example, although the silica particles are usually about 5 μm, the silica particles are considered to be composed of nanoscale silicon and silicon dioxide because of their special structure, and thus the silica particles are similar to nanoscale silicon in nature, and can be regarded as equivalent nanoscale silicon-based materials, and can be completely reacted with oxygen at high temperature to form silicon dioxide, and the test method provided by the present invention is also applicable.
The following preferred technical solutions are used as the present invention, but not as limitations on the technical solutions provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solutions.
As a preferred technical scheme of the invention, the nano silicon-based material comprises any one or a combination of at least two of nano silicon material, nano silicon oxide material, composite material formed by nano silicon and vaporizable material or composite material formed by nano silicon oxide and vaporizable material.
The nano silicon oxide material comprises a nano silicon dioxide material and/or a nano silicon oxide material.
In the present invention, the vaporizable material is a material which can volatilize or react at high temperature to generate a gas, such as a carbon material or a polymer material. Typical composite materials formed from nano-silicon and vaporizable materials include, but are not limited to, carbon-silicon composites, polymeric-nano-silicon composites, and the like. Typical composite materials formed from nano-silicon oxides and vaporizable materials include, but are not limited to, carbon-nano-silicon dioxide composites, carbon-nano-silicon oxide composites, polymer-nano-silicon dioxide composites, polymer-nano-silicon oxide composites, and the like.
Preferably, the primary particle size of the nano silicon-based material is below 500nm, for example 500nm, 300nm, 200nm or 100nm, etc.
In the preferred embodiment of the present invention, in the step (1), the weight of the nano silicon-based material sample is 0.5 to 2.0g, for example, 0.5g, 0.8g, 1g, 1.2g, 1.4g, 1.6g, 1.8g or 2.0g, etc., but the present invention is not limited to the listed values, and other non-listed values within the range of the values are equally applicable.
Preferably, in step (1), the weighing is accurate to 0.0001g.
Preferably, in step (1), the container is a polytetrafluoroethylene beaker.
Preferably, in step (1), the acid is any one or a combination of at least two of nitric acid, hydrochloric acid or sulfuric acid, typically but not limited to: a combination of nitric acid and hydrochloric acid, a combination of hydrochloric acid and sulfuric acid, a combination of nitric acid and sulfuric acid, and the like.
Preferably, in step (1), the acid is added in an amount of 10 to 20mL, for example, 10mL, 12mL, 14mL, 16mL, 18mL, 20mL, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, in the step (1), the heating treatment is kept for 10 to 50 minutes, for example, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, etc., after heating the liquid phase to boiling, but the heating treatment is not limited to the listed values, and other non-listed values within the range of values are equally applicable. In the invention, the metal in the nano silicon-based material can be dissolved completely after the nano silicon-based material is heated to boiling (micro boiling) and then kept for a period of time.
In the preferred embodiment of the present invention, in the step (1), the filter paper is medium-speed quantitative filter paper.
Preferably, in step (1), the filtration is hot filtration.
Preferably, in step (1), further comprising: after filtration the vessel and filter paper are washed with water more than 5 times, e.g. 5, 6, 7 or 8 times etc. Washing more than 5 times ensures complete transfer of the solids to the filter paper.
In the preferred embodiment of the present invention, in the step (2), the heat-resistant container is a crucible.
Preferably, in the step (2), the heat-resistant container is a heat-resistant container having a constant weight. In the invention, the constant weight means that the weight difference between the two times is less than 0.3mg.
Preferably, in the step (2), the heating temperature is 350 to 450 ℃, for example 350 ℃, 360 ℃, 370 ℃, 380 ℃, 390 ℃, 400 ℃, 410 ℃, 420 ℃, 430 ℃, 440 ℃, 450 ℃ or the like, but not limited to the values listed, and other values not listed in the range of values are equally applicable, preferably 400 ℃.
Preferably, in step (2), the heating is by heating with an electric hot plate and isolating the heat resistant container from the electric hot plate with an asbestos mesh.
Preferably, in step (2), the cooling reduces the temperature to 20-30 ℃, i.e. to room temperature.
In a preferred embodiment of the present invention, in the step (3), the oxidizing atmosphere includes an oxygen atmosphere and/or an air atmosphere.
Preferably, in the step (3), the adding method of the oxidizing atmosphere is actively introducing the oxidizing atmosphere or naturally inhaling the oxidizing atmosphere.
Preferably, in step (3), the firing is performed in a box furnace or a tube furnace.
In the step (3), the firing comprises three heating stages, and the temperatures of the three heating stages are sequentially increased. The first heating temperature of the three-stage heating is the lowest here for ensuring the volatile removal; the second stage heating temperature is higher than the first stage heating temperature for ensuring complete oxidation removal of carbon; the third stage is heated at the highest temperature to ensure complete oxidation of the silicon.
Preferably, the temperature of the first stage heating is 100-400 ℃, such as 100 ℃, 200 ℃, 300 ℃, 400 ℃ or the like, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the first heating period is 2.4-3.6 hours, such as 2.4 hours, 2.8 hours, 3 hours, 3.2 hours, 3.4 hours, or 3.6 hours, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the first stage heating is at 100 ℃, 200 ℃ and 400 ℃ for 1h, respectively.
Preferably, the temperature of the second stage heating is 850 to 950 ℃, for example 850 ℃, 860 ℃, 870 ℃, 880 ℃, 890 ℃, 900 ℃, 910 ℃, 920 ℃, 930 ℃, 940 ℃, 950 ℃, or the like, but is not limited to the values listed, and other values not listed in the range of values are equally applicable, preferably 900 ℃.
Preferably, the second heating period is 1.8-2.2h, such as 1.8h, 1.9h, 2.0h, 2.1h or 2.2h, etc., but is not limited to the recited values, and other non-recited values within the range are equally applicable, preferably 2h.
Preferably, the temperature of the third stage heating is above 1000 ℃, e.g. 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃, 1400 ℃ or the like.
Preferably, the third heating period is 4-8 hours, such as 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc., but is not limited to the recited values, and other non-recited values within the range are equally applicable.
In the invention, the concentration and the reaction temperature of the oxidizing atmosphere are improved, and the reaction rate can be improved.
In the step (4), the temperature is reduced to 20-30 ℃, i.e. to room temperature.
Preferably, in the step (4), after the temperature is reduced to below 200 ℃, the heat-resistant container is taken out together with the firing product and is placed in a dryer to be cooled to 20-30 ℃.
Preferably, in step (4), the weighing is accurate to 0.0001g.
As a preferred embodiment of the present invention, the method further comprises the step (4'): repeating the step (3) and the step (4) until the total weight of the heat-resistant container and the burning product is constant. In the invention, the constant weight means that the weight difference between the two times is less than 0.3mg.
As a further preferable technical scheme of the test method of the present invention, the method comprises the steps of:
(1) Weighing 0.5-2.0g of nano silicon-based material sample, placing the sample in a polytetrafluoroethylene beaker, heating with 10-20mL of acid, heating for 10-50min after heating a liquid phase to boiling, filtering with filter paper while the liquid phase is hot, washing the beaker and the filter paper with water for more than 5 times after filtering, and transferring solids to the filter paper to obtain filter residues;
(2) Transferring the filter paper and filter residues in the step (1) into a crucible with constant weight, heating the crucible with an electric hot plate at 400 ℃ and separating the crucible from the electric hot plate with an asbestos net, heating the crucible until the filter paper is carbonized to obtain a heated product, and then cooling the crucible to 20-30 ℃;
(3) Firing the crucible in the step (2) and a heating product in an oxidizing atmosphere, wherein the firing comprises three sections of heating, the first section of heating is respectively carried out at 100 ℃, 200 ℃ and 400 ℃, the second section of heating is carried out at 900 ℃ for 2 hours, the third section of heating is carried out at more than 1000 ℃ for 4-8 hours, and the nano silicon-based material sample is completely converted into silicon dioxide, so as to obtain a firing product;
the method for adding the oxidizing atmosphere comprises actively introducing the oxidizing atmosphere or naturally sucking the oxidizing atmosphere;
(4) Cooling the crucible and the firing product in the step (2) to below 200 ℃, taking out the crucible and the firing product together, placing the crucible and the firing product in a dryer for cooling to 20-30 ℃, and weighing to obtain the total weight of the crucible and the firing product;
(4') repeating the steps (3) and (4) until the total weight of the heat-resistant container and the firing product is constant;
(5) According to the methods of the step (1), the step (2), the step (3), the step (4) and the step (4'), a blank experiment is carried out without using a nano silicon-based material sample, and the weight gain of a blank experiment crucible is obtained;
(6) The silicon content in the nano silicon-based material sample is calculated according to the following formula:
wherein Si% is the silicon content in the nano silicon-based material sample, and the weight percent is the silicon content in the nano silicon-based material sample;
m 2 the total weight of crucible and firing product, unit: g;
m 1 the weight of the crucible is as follows: g;
m 0 weight gain of the crucible is used for blank experiments, and the unit is: g;
m is the weight of the nano silicon-based material sample, and the unit is: g.
compared with the prior art, the invention has the following beneficial effects:
(1) The method for testing the silicon content in the nano silicon-based material has the advantages of accurate detection, high precision, simple and convenient operation and wide detection range, can measure the silicon content in the nano silicon-based material to reach 0-100%, and fills the technical blank of the silicon content test of the nano silicon-based material;
(2) The method for testing the silicon content in the nano silicon-based material has the advantages of few steps, short flow, reduced risk of introducing pollution or sample loss in the operation process, and greatly improved testing efficiency;
(3) The method for testing the silicon content in the nano silicon-based material provided by the invention does not need perchloric acid and hydrofluoric acid, so that the operation danger and the environmental pollution are reduced;
(4) The method for testing the silicon content in the nano silicon-based material provided by the invention does not need to filter insoluble silicic acid, reduces the operation difficulty, greatly improves the precision of the test result, and ensures that the deviation reaches the level below 0.2 wt%.
Drawings
FIG. 1 is a schematic flow chart of a method for testing the silicon content in a nano silicon-based material according to embodiment 1 of the present invention;
fig. 2a is an XRD scan (cristobalite phase) of the burned product obtained after the burning operation in step (3) in the method for testing silicon content in nano silicon-based material according to example 1 of the present invention;
fig. 2b is an XRD scan (tridymite phase) of the burned product obtained after the burning operation in step (3) in the method for measuring silicon content in nano silicon-based material according to example 1 of the present invention.
Detailed Description
For better illustrating the present invention, the technical scheme of the present invention is convenient to understand, and the present invention is further described in detail below. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.
The following are exemplary but non-limiting examples of the invention:
example 1
The equipment, reagents and tools used in this example were as follows:
box atmosphere furnace: oxygen cylinder, pressure reducing valve and flow controller
Temperature-controlled electric heating plate
High temperature corundum crucible: clamp with crucible
Asbestos net
Dryer
An electronic balance: the sensing amount is 0.0001g
Glass funnel: diameter of 75mm
Medium-speed quantitative filter paper
Glass beaker: 200mL
Polytetrafluoroethylene beaker: 100mL of
Nitric acid: high-grade pure liquid transfer device with bottle mouth
Hydrochloric acid: high-grade pure liquid transfer device with bottle mouth
Pure water: bottle with washing function
The specific method for testing the silicon content in the nano silicon-based material in the embodiment is as follows:
(1) The high temperature corundum crucible is burned at 1200 ℃ to obtain constant weight, the constant weight is recorded to be accurate to 0.0001g, and the corundum crucible is placed in a dryer for standby. About 1.0g of the nano silicon-based material sample is weighed into a polytetrafluoroethylene beaker to the nearest 0.0001g. 2 replicates were weighed for each sample, i.e., 2 replicates were made for each sample. 3.0mL of nitric acid and 9.0mL of hydrochloric acid are added into a polytetrafluoroethylene beaker with a sample, and then the mixture is placed on a temperature-controlled electric heating plate and heated to be slightly boiled for 10 to 20 minutes. The beaker was removed and cooled slightly for 2-3 minutes, filtered in a glass beaker with medium speed quantitative filter paper, and the beaker and filter paper were rinsed with pure water more than 5 times to ensure that all solids were transferred to the filter paper.
(2) Transferring the filter paper and the filter residue into a high-temperature corundum crucible with constant weight, separating by using an asbestos screen, heating and drying the crucible at 400 ℃ on an electric hot plate until the filter paper is carbonized, taking down the high-temperature corundum crucible with the filter paper and the filter residue, and cooling the crucible to room temperature (25 ℃).
(3) The high-temperature corundum crucible with the filter paper and filter residues is carefully placed into a box-type atmosphere furnace, oxygen is introduced, and the firing is carried out. Setting a burning temperature program: the initial temperature is 50 ℃ to 10 minutes to 100 ℃, the heat preservation is 60 minutes to 20 minutes to 200 ℃, the heat preservation is 60 minutes to 30 minutes to 400 ℃, the heat preservation is 60 minutes to 50 minutes to 900 ℃, the heat preservation is 120 minutes to 1200 ℃, the heat preservation is 480 minutes, the heating is stopped, and the natural cooling is performed.
(4) Stopping oxygen introduction when the atmosphere furnace stops heating and the temperature is reduced to below 200 ℃, opening the furnace door, taking out by using clean crucible tongs, placing in a dryer, and cooling to room temperature (25 ℃). The total weight of crucible and firing product was weighed and recorded to the nearest 0.0001g. Putting the crucible into an atmosphere furnace, introducing oxygen, and setting a temperature program: the initial temperature is 50 ℃ to 20 minutes to 200 ℃, the heat preservation is performed for 30 minutes to 20 minutes to 400 ℃, the heat preservation is performed for 30 minutes to 50 minutes to 900 ℃, the heat preservation is performed for 60 minutes to 120 minutes to 1200 ℃, the heat preservation is performed for 240 minutes, the heating is stopped, and the natural cooling is performed.
(4') repeating the step (4) until the difference between the total weight of the crucible and the total weight of the firing product after the firing is less than or equal to 0.0003g.
(5) And (3) synchronously performing blank tests in the whole process according to the methods of the step (1), the step (2), the step (3), the step (4) and the step (4'), wherein the blank tests are identical to the sample test steps except that no sample is added.
(6) The silicon content test results were calculated as follows:
wherein:
si%: silicon content in the sample, wt%;
m 2 : the total weight of the crucible and the product after constant weight, g;
m 1 : crucible weight, g;
m 0 : blank weight gain, g;
m: sample weight, g;
0.4675: mass fraction of silicon element in the silicon dioxide.
The flow chart of the method for testing the silicon content in the nano silicon-based material provided by the embodiment is shown in fig. 1.
According to the method, 7 groups of nano silicon-based material samples are tested, the samples are nano silicon/carbon composite materials, and the particle size of primary particles of the samples is below 200 nm.
The results of the sample testing method of this example are shown in table 1.
TABLE 1
Because there are no suitable standards and pure products, the accuracy of the results cannot be directly verified. The sample was scanned by XRD (X-ray diffractometer) to obtain a burned product, the scan is shown in FIG. 2a and FIG. 2b, the XRD scan of FIG. 2a shows characteristic peaks of cristobalite phase product, the scan of FIG. 2b shows characteristic peaks of tridymite phase product, and the characteristic peaks of elemental silicon are found in both FIG. 2a and FIG. 2 b. XRD scanning analysis shows that the product of the nano silicon-based material sample after firing is a mixture of cristobalite and tridymite, the main component is cristobalite, a small amount of tridymite exists, and no elemental silicon exists.
Example 2
The equipment, reagents and tools used in this example were the same as those used in example 1.
The specific method for testing the silicon content of the nano silicon-based material according to this embodiment is described with reference to embodiment 1, wherein in the step (3), the highest temperature in the set firing temperature procedure is 1100 ℃.
According to the method, 7 groups of nano silicon-based material samples are tested, the samples are nano silicon oxide/carbon composite materials, and the particle size of primary particles of the samples is below 500 nm.
The results of the sample testing method of this example are shown in table 2.
TABLE 2
Example 3
The equipment, reagents and tools used in this example were the same as those used in example 1.
The specific method for testing the silicon content in the nano silicon-based material in the embodiment is as follows:
(1) The high temperature corundum crucible is burned at 1200 ℃ to obtain constant weight, the constant weight is recorded to be accurate to 0.0001g, and the corundum crucible is placed in a dryer for standby. About 0.5g of nano silicon-based material sample is weighed into a polytetrafluoroethylene beaker to the nearest 0.0001g. 2 replicates were weighed for each sample, i.e., 2 replicates were made for each sample. To a polytetrafluoroethylene beaker containing the sample, 10mL of nitric acid was added, and then placed on a temperature-controlled electric hot plate, and heated slightly for 10 minutes. The beaker was removed and cooled slightly for 2-3 minutes, filtered in a glass beaker with medium speed quantitative filter paper, and the beaker and filter paper were rinsed with pure water more than 5 times to ensure that all solids were transferred to the filter paper.
(2) Transferring the filter paper and the filter residue into a high-temperature corundum crucible with constant weight, separating by using an asbestos screen, heating and drying at 350 ℃ on an electric plate until the filter paper is carbonized, taking down the high-temperature corundum crucible with the filter paper and the filter residue, and cooling to room temperature (20 ℃).
(3) The high-temperature corundum crucible with the filter paper and filter residues is carefully placed into a box-type atmosphere furnace, oxygen is introduced, and the firing is carried out. Setting a burning temperature program: the initial temperature is 50 ℃ to 10 minutes to 100 ℃, the heat preservation is 48 minutes to 20 minutes to 200 ℃, the heat preservation is 48 minutes to 30 minutes to 400 ℃, the heat preservation is 48 minutes to 50 minutes to 850 ℃, the heat preservation is 108 minutes to 120 minutes to 1200 ℃, the heat preservation is 360 minutes, the heating is stopped, and the natural cooling is performed.
(4) Stopping oxygen introduction when the atmosphere furnace stops heating and the temperature is reduced to below 200 ℃, opening the furnace door, taking out by using clean crucible tongs, placing in a dryer, and cooling to room temperature (20 ℃). The total weight of crucible and firing product was weighed and recorded to the nearest 0.0001g.
(4') repeating the steps (3) and (4) until the difference between the total weight of the crucible and the total weight of the firing product after firing is less than or equal to 0.0003g.
(5) And (3) synchronously performing blank tests in the whole process according to the methods of the step (1), the step (2), the step (3), the step (4) and the step (4'), wherein the blank tests are identical to the sample test steps except that no sample is added.
(6) The silicon content test results were calculated as follows:
wherein:
si%: silicon content in the sample, wt%;
m 2 : the total weight of the crucible and the product after constant weight, g;
m 1 : crucible weight, g;
m 0 : blank weight gain, g;
m: sample weight, g;
0.4675: mass fraction of silicon element in the silicon dioxide.
According to the method, 3 groups of nano silicon-based material samples are tested, the samples are nano silicon materials, and the particle size of primary particles of the samples is below 200 nm.
The results of the sample testing method of this example are shown in Table 3.
TABLE 3 Table 3
Example 4
The equipment, reagents and tools used in this example were the same as those used in example 1.
The specific method for testing the silicon content in the nano silicon-based material in the embodiment is as follows:
(1) The high temperature corundum crucible is burned at 1200 ℃ to obtain constant weight, the constant weight is recorded to be accurate to 0.0001g, and the corundum crucible is placed in a dryer for standby. About 2.0g of the nano silicon-based material sample is weighed into a polytetrafluoroethylene beaker to the nearest 0.0001g. 2 replicates were weighed for each sample, i.e., 2 replicates were made for each sample. To a polytetrafluoroethylene beaker containing the sample, 20mL of hydrochloric acid was added, and then placed on a temperature-controlled electric hot plate, and heated to slight boiling for 50 minutes. The beaker was removed and cooled slightly for 2-3 minutes, filtered in a glass beaker with medium speed quantitative filter paper, and the beaker and filter paper were rinsed with pure water more than 5 times to ensure that all solids were transferred to the filter paper.
(2) Transferring the filter paper and the filter residue into a high-temperature corundum crucible with constant weight, separating by using an asbestos screen, heating and drying the crucible on an electric plate at 450 ℃ until the filter paper is carbonized, taking down the high-temperature corundum crucible with the filter paper and the filter residue, and cooling the crucible to the room temperature (30 ℃).
(3) The high-temperature corundum crucible with the filter paper and filter residues is carefully placed into a box-type atmosphere furnace, oxygen is introduced, and the firing is carried out. Setting a burning temperature program: the initial temperature is 50 ℃ to 10 minutes to 100 ℃, the heat preservation is 72 minutes to 20 minutes to 200 ℃, the heat preservation is 72 minutes to 30 minutes to 400 ℃, the heat preservation is 72 minutes to 50 minutes to 950 ℃, the heat preservation is 132 minutes to 120 minutes to 1500 ℃, the heat preservation is 240 minutes, the heating is stopped, and the natural cooling is performed.
(4) Stopping oxygen introduction when the atmosphere furnace stops heating and the temperature is reduced to below 200 ℃, opening the furnace door, taking out by using clean crucible tongs, placing in a dryer, and cooling to room temperature (30 ℃). The total weight of crucible and firing product was weighed and recorded to the nearest 0.0001g.
(4') repeating the steps (3) and (4) until the difference between the total weight of the crucible and the total weight of the firing product after firing is less than or equal to 0.0003g.
(5) And (3) synchronously performing blank tests in the whole process according to the methods of the step (1), the step (2), the step (3), the step (4) and the step (4'), wherein the blank tests are identical to the sample test steps except that no sample is added.
(6) The silicon content test results were calculated as follows:
wherein:
si%: silicon content in the sample, wt%;
m 2 : the total weight of the crucible and the product after constant weight, g;
m 1 : crucible weight, g;
m 0 : blank weight gain, g;
m: sample weight, g;
0.4675: mass fraction of silicon element in the silicon dioxide.
According to the method, 3 groups of nano silicon-based material samples are tested, the samples are nano silicon oxide materials, and the particle size of primary particles of the samples is below 500 nm.
The results of the sample testing method of this example are shown in Table 4.
TABLE 4 Table 4
According to the embodiment, the method for testing the silicon content in the nano silicon-based material provided by the invention has the advantages of accurate detection, high precision, small deviation, simplicity and convenience in operation, wide detection range, few steps and short flow, reduces the risk of introducing pollution or sample loss in the operation process, and greatly improves the testing efficiency. In addition, the method for testing the silicon content in the nano silicon-based material provided by the invention does not need perchloric acid and hydrofluoric acid, reduces operation danger and environmental pollution, does not need to filter insoluble silicic acid, reduces operation difficulty, and greatly improves the precision of a test result.
The applicant states that the detailed method of the present invention is illustrated by the above examples, but the present invention is not limited to the detailed method described above, i.e. it does not mean that the present invention must be practiced in dependence upon the detailed method described above. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.
Claims (36)
1. The method for testing the silicon content in the nano silicon-based material is characterized by comprising the following steps of:
(1) Weighing a nano silicon-based material sample, placing the sample in a container, heating the sample by using acid, filtering the sample by using filter paper, and transferring the solid to the filter paper to obtain filter residues;
(2) Transferring the filter paper and filter residues in the step (1) into a heat-resistant container, heating the filter paper until the filter paper is carbonized to obtain a heated product, and then cooling the heat-resistant container;
(3) Firing the heat-resistant container in the step (2) and a heating product in an oxidizing atmosphere, and completely converting the nano silicon-based material sample into silicon dioxide to obtain a firing product;
(4) Cooling the heat-resistant container and the firing product in the step (2), and weighing to obtain the total weight of the heat-resistant container and the firing product;
(5) A nano silicon-based material sample is not used, and blank experiments are carried out in the whole process according to the method of the previous step, so that the weight gain of the blank experiment heat-resistant container is obtained, wherein the weight gain is the weight of ash left after filter paper firing;
(6) The silicon content in the nano silicon-based material sample is calculated according to the following formula:
wherein Si% is the silicon content in the nano silicon-based material sample, and the weight percent is the silicon content in the nano silicon-based material sample;
m 2 the unit is the total weight of the heat-resistant container and the burning product: g;
m 1 the weight of the heat-resistant container is as follows: g;
m 0 weight gain of the heat-resistant container for blank experiments, unit: g;
m is the weight of the nano silicon-based material sample, and the unit is: g.
2. the method of testing of claim 1, wherein the nano-silicon-based material comprises any one or a combination of at least two of a nano-silicon material, a nano-silicon oxide material, a composite of nano-silicon and a vaporizable material, or a composite of nano-silicon oxide and a vaporizable material.
3. The method according to claim 1, wherein the primary particle size of the nano silicon-based material is 500nm or less.
4. The method according to claim 1, wherein in step (1), the weight of the nano silicon-based material sample is 0.5-2.0g.
5. The test method according to claim 1, wherein in step (1), the weighing is accurate to 0.0001g.
6. The test method of claim 1, wherein in step (1), the container is a polytetrafluoroethylene beaker.
7. The test method of claim 1, wherein in step (1), the acid is any one or a combination of at least two of nitric acid, hydrochloric acid, or sulfuric acid.
8. The method according to claim 1, wherein the acid is added in an amount of 10 to 20mL in step (1).
9. The test method according to claim 1, wherein in the step (1), the heating treatment is kept for 10 to 50 minutes after heating the liquid phase to boiling.
10. The method according to claim 1, wherein in step (1), the filter paper is medium speed quantitative filter paper.
11. The test method of claim 1, wherein in step (1), the filtering is hot filtering.
12. The test method of claim 1, wherein in step (1), further comprising: after filtration, the vessel and filter paper were washed with water more than 5 times.
13. The method according to claim 1, wherein in step (2), the heat-resistant container is a crucible.
14. The test method according to claim 1, wherein in the step (2), the heat-resistant container is a heat-resistant container having a constant weight.
15. The test method according to claim 1, wherein in step (2), the heating temperature is 350-450 ℃.
16. The method of claim 15, wherein in step (2), the temperature of heating is 400 ℃.
17. The test method of claim 1, wherein in step (2), the heating is performed by heating with an electric hot plate and separating the heat resistant container from the electric hot plate with an asbestos gauze.
18. The test method of claim 1, wherein in step (2), the cooling reduces the temperature to 20-30 ℃.
19. The test method according to claim 1, wherein in step (3), the oxidizing atmosphere comprises an oxygen atmosphere and/or an air atmosphere.
20. The method according to claim 1, wherein in the step (3), the method of adding the oxidizing atmosphere is actively introducing the oxidizing atmosphere or naturally inhaling the oxidizing atmosphere.
21. The test method according to claim 1, wherein in step (3), the firing is performed in a box furnace or a tube furnace.
22. The test method of claim 1, wherein in step (3), the firing comprises three heating stages, the three heating stages having sequentially increasing temperatures.
23. The method of claim 22, wherein the first heating of the three heating stages is at a temperature of 100-400 ℃.
24. The method of claim 23, wherein the first heating is for a period of 2.4 to 3.6 hours.
25. The test method of claim 23, wherein the first stage heating is at 100 ℃, 200 ℃ and 400 ℃ for 1 hour, respectively.
26. The method of claim 22, wherein the second heating of the three-stage heating is at a temperature of 850-950 ℃.
27. The method of claim 26, wherein the second stage heating is at a temperature of 900 ℃.
28. The method of claim 26, wherein the second heating is for a period of 1.8-2.2 hours.
29. The method of claim 28, wherein the second heating is for a period of 2 hours.
30. The method of claim 22, wherein the third heating of the three heating stages is at a temperature above 1000 ℃.
31. The method of claim 30, wherein the third heating is for a period of 4-8 hours.
32. The test method of claim 1, wherein in step (4), the cooling reduces the temperature to 20-30 ℃.
33. The test method according to claim 1, wherein in the step (4), the cooling is performed by taking out the heat-resistant container together with the burned product after the temperature is lowered to 200 ℃ or less, and cooling to 20-30 ℃ in a dryer.
34. The test method of claim 1, wherein in step (4), the weighing is accurate to 0.0001g.
35. The test method of claim 1, further comprising the step (4'): repeating the step (3) and the step (4) until the total weight of the heat-resistant container and the burning product is constant.
36. The test method according to claim 1, characterized in that it comprises the steps of:
(1) Weighing 0.5-2.0g of nano silicon-based material sample, placing the sample in a polytetrafluoroethylene beaker, heating with 10-20mL of acid, heating for 10-50min after heating a liquid phase to boiling, filtering with filter paper while the liquid phase is hot, washing the beaker and the filter paper with water for more than 5 times after filtering, and transferring solids to the filter paper to obtain filter residues;
(2) Transferring the filter paper and filter residues in the step (1) into a crucible with constant weight, heating the crucible with an electric hot plate at 400 ℃ and separating the crucible from the electric hot plate with an asbestos net, heating the crucible until the filter paper is carbonized to obtain a heated product, and then cooling the crucible to 20-30 ℃;
(3) Firing the crucible in the step (2) and a heating product in an oxidizing atmosphere, wherein the firing comprises three sections of heating, the first section of heating is respectively carried out at 100 ℃, 200 ℃ and 400 ℃, the second section of heating is carried out at 900 ℃ for 2 hours, the third section of heating is carried out at more than 1000 ℃ for 4-8 hours, and the nano silicon-based material sample is completely converted into silicon dioxide, so as to obtain a firing product;
the method for adding the oxidizing atmosphere comprises actively introducing the oxidizing atmosphere or naturally sucking the oxidizing atmosphere;
(4) Cooling the crucible and the firing product in the step (2) to below 200 ℃, taking out the crucible and the firing product together, placing the crucible and the firing product in a dryer for cooling to 20-30 ℃, and weighing to obtain the total weight of the crucible and the firing product;
(4') repeating the steps (3) and (4) until the total weight of the heat-resistant container and the firing product is constant;
(5) According to the methods of the step (1), the step (2), the step (3), the step (4) and the step (4'), a blank experiment is carried out without using a nano silicon-based material sample, and the weight gain of a blank experiment crucible is obtained;
(6) The silicon content in the nano silicon-based material sample is calculated according to the following formula:
wherein Si% is the silicon content in the nano silicon-based material sample, and the weight percent is the silicon content in the nano silicon-based material sample;
m 2 the total weight of crucible and firing product, unit: g;
m 1 the weight of the crucible is as follows: g;
m 0 weight gain of the crucible is used for blank experiments, and the unit is: g;
m is the weight of the nano silicon-based material sample, and the unit is: g.
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| US20100167921A1 (en) * | 2006-09-06 | 2010-07-01 | World Minerals, Inc. | Process for Roasting Diatomaceous Earth Ore to Reduce Organic Content |
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| JP2004069413A (en) * | 2002-08-05 | 2004-03-04 | Sumitomo Metal Mining Co Ltd | Method for determining the quantity of silicon in organic silicon compound |
| JP2011020886A (en) * | 2009-07-15 | 2011-02-03 | Shinetsu Quartz Prod Co Ltd | Silica container and method for producing the same |
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