A kind of wimet detection method of paraffin content in the powder
Technical field
The present invention relates to a kind of fast detecting wimet with the method for paraffin content in the powder, relate in particular to the detection method that a kind of wimet is used paraffin content in the powder.
Background technology
In the preparation process of wimet; usually can be with paraffin as the low temperature moulding agent; the bonding wimet starting powder such as starting material such as cobalt powder and tungsten carbide (being called hard alloy material) at low temperature moulding; then through steps such as dewaxing and high temperature sinterings; prepare last carbide-tipped tool etc., wherein moulding is the important step in the preparation hard alloy process.Particularly, paraffin with the form of paraffin organism (gasoline, hexane etc.) with mix through wet ball grinding and dried hard alloy material, the powder that has wrapped up paraffin then is bonded together compression moulding, is used for follow-up high temperature dewaxing and sintering.
Paraffin mainly is made up of normal alkane, and institute comprises methyl and methylene at near-infrared region 2930cm
-1There is characteristic absorption.Wimet has thermogravimetry and extraction with the detection method of paraffin content in the powder.Thermogravimetry is: under hydrogen shield atmosphere, utilize the character of paraffin boiling point lower (300~500 ℃), continue heating its gasification is separated, calculate the content of paraffin then according to mass loss.Extraction back gas phase-mass spectrometer coupling method is: will extract in organic solvent with the paraffin of separating the powder from wimet, and detect the content of paraffin then with the method for gas phase-mass spectrometer coupling.Yet all there is certain defective in these known two kinds of methods at present, and the former detection time is long, and dangerous in hydrogen atmosphere, and latter's gas phase-mass spectrometer coupling equipment price is expensive and react requirement than higher.
Summary of the invention
For addressing the above problem, the present invention aims to provide the detection method that a kind of wimet is used paraffin content in the powder, and weak point consuming time, convenient and safe and reliable results can be used in and detect a plurality of samples simultaneously, and be with low cost.
The present invention utilizes methyl in the paraffin and methylene at near-infrared region 2930cm
-1The characteristic that has characteristic absorption provides the detection method of a kind of wimet with paraffin content in the powder, may further comprise the steps:
(1) sets up working curve: take by weighing the paraffin standard model, add low-grade fever dissolving extremely fully in the organic solvent, be mixed with the paraffin standard solution, prepare the paraffin standard solution series gradient dilution solution of different paraffin concentration subsequently respectively, moving in the cuvette, is 2930cm in infrared luminosity oil content analyzer wave number
-1Each paraffin standard solution series gradient dilution solution absorbency is measured at the place respectively, is horizontal ordinate with paraffin concentration, and absorbance is ordinate drawing curve;
(2) detect wimet with paraffin content in the powder: take by weighing wimet powder testing sample, adding lytic agent low-grade fever to hard alloy material separates with paraffin, add organic solvent subsequently, fully shake up, change in the separating funnel and vibrate, treat standing demix after, taking off layer extract moves in the volumetric flask, adding described organic solvent constant volume, pipette mixed solution and enter in the cuvette from volumetric flask, is 2930cm in infrared luminosity oil content analyzer wave number
-1Absorbance is measured at the place, calculates wimet paraffin content in the powder with reference to working curve.
Paraffin is water insoluble, and solubleness is lower in pure and mild ketone, is soluble in phenixin, methenyl choloride, ether, benzene, carbon disulphide, various mineral oil and the most of vegetable oil.Preferably, organic solvent of the present invention is selected from one or more in phenixin, methenyl choloride, ether, benzene and the carbon disulphide.More preferably, organic solvent is the special-purpose phenixin of infrared luminosity oil content analyzer, and this phenixin is 2930cm in wave number
-1Place's light absorption value is 0.001~0.03.Paraffin has higher solubleness in phenixin, its solubleness is 40g under the normal temperature, its solubleness is 60g in the time of 50 ℃, therefore carry out low-grade fever after adding phenixin among the present invention, the solubleness of paraffin can be far longer than the addition that wimet is used paraffin in the powder, thereby paraffin is dissolved fully.
In the step (1), the paraffin standard model should be identical with the paraffin model in the testing sample.For obtaining working curve more accurately, preferably, the quality that takes by weighing the paraffin standard model is accurate to 0.0001g.
" be mixed with the paraffin standard solution " and refer to the paraffin standard model that will be dissolved in behind the organic solvent, move in the volumetric flask, to scale, the constant volume mixing is mixed with the paraffin standard solution with organic solvent diluting.Preferably, the concentration of paraffin is 1000mg/L in the paraffin standard solution.
" prepare the paraffin standard solution series gradient dilution solution of different paraffin concentration " and refer to pipette respectively the paraffin standard solution of certain volume, place a plurality of volumetric flasks respectively, to scale, the constant volume mixing is mixed with the paraffin dilute solution of serial gradient concentration with organic solvent diluting.Preferably, serial gradient is 4.More preferably, the concentration of paraffin standard solution series gradient dilution solution is respectively 10mg/L, 20mg/L, 30mg/L and 40mg/L.
Utilizing infrared luminosity oil content analyzer to measure each paraffin standard solution series gradient dilution solution absorbency respectively, is horizontal ordinate with paraffin concentration, and absorbance is ordinate drawing curve.Preferably, cuvette is quartz colorimetric utensil.
In the step (2), testing sample is the wimet powder, and described wimet powder is coated on the hard alloy material surface by paraffin and is formed, and hard alloy material can be cobalt powder and tungsten-carbide powder etc.For obtaining to detect data more accurately, preferably, the quality that takes by weighing testing sample is accurate to 0.0001g.
" adding lytic agent low-grade fever to hard alloy material separates with paraffin " refers to add lytic agent, and heating (being generally under 50~60 ℃ of temperature) to hard alloy material separates with paraffin.Lytic agent can be salpeter solution, and preferably, lytic agent is that analytically pure nitric acid and water form by the equal volume mixed preparing.Preferably, the solid-to-liquid ratio of testing sample and lytic agent (g/L) is 50: 1.
" add organic solvent subsequently, fully shake up " and refer to add organic solvent low-grade fever to paraffin and be dissolved in fully in this organic solvent.Preferably, organic solvent is selected from one or more in phenixin, methenyl choloride, ether, benzene and the carbon disulphide.More preferably, organic solvent is the special-purpose phenixin of infrared luminosity oil content analyzer, and this phenixin is 2930cm in wave number
-1Place's light absorption value is 0.001~0.03.Repeat to add the organic solvent operation once.
" change in the separating funnel and vibrate, treat standing demix after, take off layer extract and move in the volumetric flask, add the organic solvent constant volume " refer to that the mixed solution that will add after organic solvent shakes up extracts, lower floor's extract is the comparatively pure paraffin that is purified into.This extraction process number of times is not limit, and is extracted out for the paraffin in the assurance testing sample is as much as possible, can repeatedly add organic solvent in the mixed solution that adds lytic agent, and gradation extracts the back and obtains many parts of lower floor's extracts.Lower floor's extract is moved in the volumetric flask, be settled to certain volume by adding organic solvent, be used for calculating the extension rate of testing sample paraffin.Preferably, the paraffin in per unit mass (mg) testing sample is dissolved in the organic solvent of 1L behind the constant volume.
Pipetting a small amount of mixed solution and enter in the cuvette from volumetric flask, is 2930cm in infrared luminosity oil content analyzer wave number
-1Absorbance is measured at the place, calculates wimet paraffin content in the powder with reference to working curve.
Preferably, step (2) is done blank test in company with sample.Be reference solution with the blank test sample, can eliminate reagent and disturb, guarantee precision of test result.
The present invention provides the detection method of paraffin content in a kind of wimet usefulness powder first, adopts the paraffin in the organic solvent extraction separation wimet usefulness powder, and measures absorbance at infrared luminosity oil content analyzer, calculates paraffin content with reference to working curve.This detection method weak point consuming time, convenient and safe and reliable results can be used in and detect a plurality of samples simultaneously, and be with low cost.
Description of drawings
Fig. 1 is the working curve diagram of the embodiment of the invention one.
Embodiment
The following stated is preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also are considered as protection scope of the present invention.
Embodiment one
A kind of wimet detection method of paraffin content in the powder may further comprise the steps:
(1) sets up working curve
Take by weighing 0.2500g paraffin standard model, (this phenixin is 2930cm in wave number to dissolving fully to add in the special-purpose phenixin of infrared luminosity oil content analyzer low-grade fever
-1Place's light absorption value is 0.001~0.03), move in the 250mL volumetric flask, be diluted to scale with phenixin, the constant volume mixing, being mixed with paraffin concentration is the paraffin standard solution of 1000mg/L.Pipette 1.0mL, 2.0mL, 3.0mL and 4.0mL paraffin standard solution respectively in one group of 100mL volumetric flask, be mixed with the paraffin standard solution series gradient dilution solution (paraffin concentration is 4 gradients, is respectively 10mg/L, 20mg/L, 30mg/L and 40mg/L) of different paraffin concentration.Paraffin standard solution series gradient dilution solution is moved into respectively in the quartz colorimetric utensil, is 2930cm in infrared luminosity oil content analyzer wave number
-1Each paraffin standard solution series gradient dilution solution absorbency is measured at the place respectively, is horizontal ordinate with paraffin concentration, and absorbance is ordinate drawing curve, and working curve is seen Fig. 1, and Fig. 1 working curve equation is: A=0.0159C+0.0103.
(2) detect wimet paraffin content in the powder
Take by weighing 1.00g (m
0) testing sample, be accurate to 0.0001g.Place the 400mL beaker.Add 10mL water and 10mL and analyze pure nitric acid, low-grade fever to hard alloy material separates with paraffin.Add the 10mL phenixin, fully shake up, repeat this operation once.Change the 20s that vibrates in the 125mL separating funnel over to, treat standing demix after, take off a layer extract.Add phenixin in the mixed solution that adds nitric acid again and extract, take off a layer extract.Lower floor's extract of collecting respectively for twice is moved into 100mL (V
0) in the volumetric flask, add phenixin and be diluted to scale, the constant volume mixing.At this moment, divide the solution to be measured of getting 5mL from volumetric flask in the 50mL volumetric flask, be diluted to scale with phenixin, the constant volume mixing is therefrom drawn small volume of solution subsequently and is moved in the quartz colorimetric utensil, is 2930cm in infrared luminosity oil content analyzer wave number
-1The place, measuring absorbance is 0.3283, calculates wimet paraffin content in the powder with reference to Fig. 1 working curve.
Be calculated as follows the wimet massfraction of paraffin in the powder, the result represents with %.
In the formula:
ρ---check in the mass concentration of paraffin on working curve, unit is every liter (mg/L) of milligram;
V
0---testing sample liquid cumulative volume, unit are milliliter (mL);
m
0---the quality of testing sample, unit is gram (g);
5---divide the testing sample liquid volume of getting, unit is milliliter (mL);
50---testing sample liquid branch is got the mensuration volume behind the constant volume, and unit is milliliter (mL).
Particularly, Fig. 1 working curve equation is: A=0.0159C+0.0103, calculate the mass concentration ρ of paraffin by curvilinear equation, and be calculated as follows:
ρ value substitution formula calculates the massfraction of paraffin:
Effect embodiment
(1) quantitative detecting reliability
In order to verify the reliability of the inventive method, this experiment has adopted thermogravimetry and the inventive method to carry out control experiment to all testing samples simultaneously.
The equal replicate determination of each testing sample is 2 times in each method, averages as the quantitative experiment data.Control experiment data such as the table 1 of thermogravimetry and the inventive method.
The control experiment of table 1 thermogravimetry and the inventive method
Sample number into spectrum |
Thermogravimetry wax content (%) |
The inventive method wax content (%) |
Relative deviation |
1 |
1.05 |
1.00 |
4.87% |
2 |
1.03 |
1.02 |
0.98% |
3 |
1.45 |
1.46 |
0.69% |
4 |
1.42 |
1.41 |
0.70% |
5 |
2.02 |
1.98 |
2.00% |
6 |
1.99 |
2.02 |
1.49% |
7 |
2.50 |
2.48 |
0.80% |
8 |
2.45 |
2.46 |
0.41% |
9 |
3.02 |
2.95 |
2.35% |
10 |
2.96 |
2.98 |
0.67% |
11 |
3.96 |
3.99 |
0.75% |
12 |
3.90 |
3.96 |
1.53% |
Thermogravimetry requires that maximum deviation must not be greater than 5% of mean value between twice measurement result.As can be known from Table 1, adopt the inventive method to detect wimet with the paraffin content in the powder, compare its relative deviation in 5% with thermogravimetry.This deviation is in allowed limits, is rational deviation, and is consequently reliable.
For further verifying the accuracy of testing result, designed the mark-on recovery test.The mark-on recovery test is:, add paraffin content and be respectively 0.01g, 0.02g and 0.03g with the paraffin standard substance that adds known quantity in the powder to wimet, be numbered 1#, 2#, 3#.Measure according to the inventive method, it the results are shown in Table 2.
Table 2 mark-on recovery test
The sample title |
Sample weighting amount g |
Add paraffin amount g |
Record paraffin amount g |
Recovery % |
1# |
1.0 |
0.01 |
0.0098 |
98 |
2# |
1.0 |
0.02 |
0.0205 |
102.5 |
As seen from Table 2, recovery of standard addition shows that 98%~103% its testing result is accurately.
(2) linear relationship, the recovery and precision
The paraffin standard solution being prepared the paraffin standard solution series gradient dilution solution of different paraffin concentration, use 4cm quartz colorimetric utensil sample introduction, is horizontal ordinate with the absorbance, and paraffin concentration is ordinate, and drawing curve, its linearly dependent coefficient are 0.9995.
Wimet is with adding the paraffin standard substance in the powder, and the preparation wax content is 1.0%, 2.0% and 3.0% 3 kind of sample, is numbered 1# respectively, 2#, 3#.Measure according to the inventive method, its relative standard deviation sees Table 3.
The test of table 3 sample precision
By table 2 and table 3 as seen, detect wimet with the paraffin content in the powder with the inventive method, its accuracy and precision are all comparatively desirable.