CN111208167A - Preparation method and application of standard substance of Curie point of Aleamer alloy - Google Patents
Preparation method and application of standard substance of Curie point of Aleamer alloy Download PDFInfo
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Abstract
The invention discloses a preparation method of an alexandrite Curie point standard substance, wherein the alexandrite alloy is used as a raw material, the components and the content of the raw material are analyzed and confirmed, and the raw material is purified by a vacuum distillation method according to different boiling points and saturated vapor pressures of the components; carrying out uniformity initial detection on the purified raw materials with a specific quantitative value, and screening out the raw materials with uniform Curie temperature as candidate standard substances; and (3) carrying out uniformity inspection, stability inspection, quantity value determination and uncertainty analysis on the candidate standard substance according to the metrological requirements, and if the uniformity, the stability and the uncertainty meet the requirements, the quantity value is accurate and stable and meets the metrological characteristics, namely the Alimei alloy Curie point standard substance. The standard substance obtained by the preparation method disclosed by the invention is accurate and stable in characteristic quantity value, can be used for verification or calibration of related instruments and evaluation of analysis methods, and provides an important technical support for detection and supervision management in the fields of materials, environmental protection, biological medicine, food inspection and the like.
Description
Technical Field
The invention belongs to the technical field of metering, relates to a standard substance, and particularly relates to a preparation method and application of an alemter alloy Curie point standard substance.
Background
In recent years, the development of magnetic materials is very rapid, the application is wide, and particularly, the continuous emergence of novel magnetic materials plays a great role in promoting the technological progress of modern industry, so that the magnetic materials become one of the hot areas for research and study of scientists in various countries around the world. The curie temperature, one of the most important intrinsic parameters of a magnetic material, is also the main physical parameter of the intrinsic magnetic properties of the magnetic material, and reflects the change of a ferromagnetic substance into a paramagnetic substance, i.e. the change from magnetic to non-magnetic, of the ferromagnetic material with the increase of temperature. Therefore, the method plays a very important role in the research of magnetic materials, and has important significance in deeply researching and measuring the Curie temperature of the materials.
Thermogravimetric analyzers (TG) are widely used for measuring the curie temperature of magnetic materials, and the instrument needs to be calibrated in order to ensure the accuracy of the obtained numerical value. At present, the temperature calibration of the thermogravimetric analyzer uses a substance (i.e., a standard substance) that has a magnetic change at a fixed temperature and can also react the change on a thermogravimetric (thermogravimetric) TG curve, such as a magnetic alloy, nickel, iron, and the like, and the temperature calibration of the thermogravimetric analyzer is realized by measuring the curie temperature of a specific magnetic material.
In the existing standard substances, China metrology science research institute develops three Curie point standard substances of alemte alloy (153.8 ℃), nickel (358.6 ℃) and iron (772.0 ℃), but along with the fact that the temperature measurement range of a thermogravimetric analyzer on the market is wider and wider, the temperature of the thermogravimetric analyzer can reach 1500 ℃, for example, Q650 and Q600 series of TA company, the variety of the Curie point standard substance is urgently needed to be perfected, and the correctable temperature range is enlarged.
In the prior art, patent CN1198127C discloses a standard sample for temperature calibration of a thermogravimetric analyzer and a preparation method thereof, wherein the standard sample consists of two samples, one sample is calibrated at 29 ℃ and the other is calibrated at 90.4 ℃, but the two samples are both prepared by a sol-gel method, are nonmetal standard substances and have no measurement traceability.
Disclosure of Invention
The invention aims to provide a preparation method and application of an alexandrite Curie point standard substance, so as to enrich the types of the Curie point standard substance and enlarge the calibratable temperature range.
According to one aspect of the invention, the preparation method of the Curie point standard substance of the Altemel alloy is provided, and the preparation method comprises the following specific steps:
analyzing and confirming the components and the content of the raw material by using the alemter alloy as the raw material, and purifying the raw material by adopting a vacuum distillation method according to different boiling points and saturated vapor pressures of the components;
carrying out uniformity initial detection on the purified raw materials with a specific quantitative value, and screening out the raw materials with uniform Curie temperature as candidate standard substances;
and (3) carrying out uniformity inspection, stability inspection, quantity value determination and uncertainty analysis on the candidate standard substance according to the metrological requirements, and if the uniformity, the stability and the uncertainty meet the requirements, the quantity value is accurate and stable and meets the metrological characteristics, namely the Asherman point standard substance.
In some embodiments, the vacuum distillation process is performed at a temperature of 1873K and an incubation time of 2-3 hours with a vacuum setting of 3-9 Pa.
In some embodiments, the uniformity initial test method is as follows: randomly selecting at least 3 parts of raw materials, shearing at least 2 different parts of each part of raw materials, measuring the Curie temperature of the sheared part, and judging whether the materials are uniform or not according to the measurement result.
In some embodiments, the specific steps for performing a homogeneity test on a candidate standard substance are as follows: randomly extracting not less than 11 bottles of samples from the candidate quasi-substances which are divided and numbered, and randomly extracting 3 subsamples from each bottle of samples; and measuring the Curie temperature of each subsample, and comparing the variance between groups with the variance in groups to judge whether the measured values of each group have systematic differences so as to confirm whether the candidate standard substance is uniform. The standard is considered uniform if the ratio of the between-group variance and the within-group variance is less than the cut-off value of the statistical test.
In some embodiments, the stability test comprises long term stability and short term stability, wherein long term stability is the magnitude stability of the tracked candidate standard substance for 24 months at room temperature, the short term stability simulates transportation conditions at high and low temperatures, the candidate standard substance is respectively placed in an incubator at (60 +/-5) DEG C and (60 +/-5)% RH and a refrigerator at (-4 +/-1) DEG C, and is respectively stored for one week, and the stability of one week is considered; and performing regression analysis according to the measurement result to judge whether the stability reaches the standard.
In some embodiments, the method further comprises the step of valuing the alemteric curie point standard substance, using the LGC melting point standard substance as an external standard, and performing collaborative valuing in combination with 8 laboratories.
Specifically, each laboratory instrument is qualified by the verification of a legal metering mechanism before use, and the Curie temperature testing process is traced to the LGC melting point standard substance; randomly drawing 3 packages from all samples and distributing the packages to laboratories, randomly taking 3 subsamples from each bottle by each laboratory, repeatedly testing each subsample for 3 times, and taking an average value as a result; after 8 laboratories carry out valuing, the result of the valuing is subjected to in-group suspicious value analysis, equal precision analysis, inter-group suspicious value analysis and normal distribution analysis.
In some embodiments, the uncertainty analysis comprises an uncertainty introduced by performing a fixed value experiment on the candidate standard substance, an uncertainty arising from non-uniformity of the candidate standard substance, and an uncertainty analysis arising from instability of the candidate standard substance. Wherein, the uncertainty introduced by the fixed value experiment comprises the uncertainty generated by combining fixed value repeatability with the uncertainty generated by a melting point standard substance used for fixed value.
According to a second aspect of the present invention, there is provided a curie point standard substance, which is an alexandrite curie point standard substance, produced by the above production method.
In some embodiments, the aforementioned alexandrite curie point standard substance has a curie point of 161.4 ℃, an extended uncertainty of 2 ℃, and comprises the following components in percentage by mass: 94.24 to 94.76 percent of Ni, 2.24 to 2.25 percent of Al, 1.23 to 1.45 percent of Mn and 1.54 to 2.29 percent of Si.
Compared with the existing alexandrite alloy standard substance, the difference shows that slight difference exists in component content, but the slight difference of the alexandrite alloy in component content has large influence on magnetic performance, can cause remarkable difference of Curie temperature, and the influence of each component and impurity on the Curie temperature is synergistic effect, non-single influence, and the specific expression is that:
influence of Nickel: the alloy having a low initial permeability has a wide Ni content distribution range and a high Ni content, while the alloy having a high initial permeability has a concentrated Ni content distribution and a relatively low Ni content.
Influence of manganese: mn has obvious influence on the structure of the alloy, and when the purity of the alloy is low, excessive Mn can damage the structure and generate adverse influence on the magnetic property; when the purity of the alloy is high, the high Mn content can improve the texture and the magnetic performance.
Influence of aluminum: the effect of aluminum is similar to that of silicon, and the aluminum can reduce a phase region, coarsen crystal grains, improve resistivity, reduce a magnetic anisotropy constant K, reduce iron loss and reduce magnetic induction; when the aluminum content is low, the aluminum and the nitrogen are combined to form fine and dispersed Al-N, so that the growth of crystal grains during annealing is obviously prevented, and the magnetic performance is obviously reduced; when the content of aluminum is higher, the size of a precipitated phase Al-N is larger, which is beneficial to coarsening of crystal grains.
Influence of silicon: because silicon is a non-magnetic element, the saturation magnetization is reduced due to the high content of Si, and the magnetic induction is correspondingly reduced; si obviously hinders the mobility of crystal boundaries in the recrystallization process, and the orientation difference between crystal grains is caused when the crystal boundaries migrate at a low speed; the relative influence on the mobility of the grain boundary becomes large, the selective growth among the grains in the recrystallization annealing process is promoted, and the magnetic performance is not good.
According to a third aspect of the present invention, there is provided the use of the curie point standard substance described above as a thermogravimetric analyzer or synchronous thermal analyzer temperature calibration standard substance.
The ferromagnetic Curie point standard substance obtained by the preparation method disclosed by the invention is accurate and stable in characteristic quantity value, can be used for verification or calibration of related instruments (thermogravimetric analyzers or synchronous thermal analyzers), and analysis method evaluation, and provides an important technical support for detection and supervision management in the fields of materials, environmental protection, biological medicines, food inspection and the like.
Drawings
FIG. 1 is a temperature-mass curve and a temperature-heat flow curve of In of a candidate standard substance obtained In example 1;
FIG. 2 is an appearance diagram of candidate standard substances obtained in example 1;
FIG. 3 is a graph showing the trend of the long-term stability of the candidate standard substance obtained in example 1;
FIG. 4 is a short-term stability trend plot (60. + -. 5 ℃ C.) of the candidate standards obtained in example 1;
FIG. 5 is a graph showing a trend of short-term stability (-4. + -. 1) ° C of the candidate standard substance obtained in example 1;
FIG. 6 is a graph of normal distribution test of the original data of candidate standard substance constant values obtained in example 1 in eight laboratories;
FIG. 7 is a graph of a normal distribution test of the mean value of the candidate standard substance quantitative data obtained in example 1 in eight laboratories.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Firstly, a Curie temperature test method needs to be determined, and in the invention, the Curie temperature test method and the process for determining the method are as follows:
and (3) carrying out Curie temperature test by using a synchronous thermal analyzer, shearing fragments with proper sizes from the object to be tested according to the size of the crucible before sample test, and weighing about 10mg of the sample to be tested each time. When in use, the clean tools such as tweezers and scissors are used to prevent the sample from being polluted.
(1) Instrument calibration
The instrument used for the test was a synchronous thermal analyzer. The standard substance is qualified by verification before use so as to ensure that the characteristic quantity values of the instrument and the standard substance can be traced to international units.
(2) Test method
The Magnetic Standard substance Curie Temperature is tested according to the Standard ASTM + E1582-2014 Standard practice for measuring Calibration for Thermal Analysis, JG1135-2017 thermogravimetric Analyzer assay protocol and the literature "Calibration of reference materials of aluminum, ceramic iron for Current Point" (Wang T, Wang H, Wang F, et al. Calibration of reference materials of aluminum, ceramic and iron for Current Point [ J ]. Journal of Thermal Analysis and Calibration, 2017.), "Magnetic Temperature Standards for measuring (Gallager P K, glass R, glass E L, Temperature Standard J, sample Standard J. (Journal of Thermal Analysis and Calibration, T.S. 1109) TG [ TG 3. J. (Journal of Analysis, TG 3. TG). Tracing to an indium melting point standard substance according to the Curie temperature of the Altemel alloy, wherein the melting point standard substance adopts LGC2601 (the specific parameters are shown in Table 1).
The specific test method is that the method is combined with the characteristics of the prepared standard substance by referring to the standard and the literature report method: the sample size of the magnetic standard substance was about 10 mg; adjusting the position of the magnet to make the apparent mass change of the sample about 5% before and after loading the magnet; the carrier gas is nitrogen, and the flow rate is 100 mL/min; the extrapolated end-of-transition temperature, i.e., the intersection of the tangent line drawn from the inflection point of the temperature-mass curve and the extension of the post-curie-transition baseline, was taken as the curie point measurement at the end of the experiment.
Table 1 melting point standard substances recommended for use
As shown In FIG. 1, LGC2601-In was used as an external standard substance because the melting point (156.60 ℃) of LGC2601-In was close to the theoretical Curie temperature (about 160 ℃) of Altemel. The empty sample crucible and the reference crucible were peeled off before the experiment. About 10mg of LGC2601-In was weighed, placed In a ceramic crucible, and the melting point of LGC2601-In was measured by using the procedure shown In Table 2 as a temperature raising means. The same procedure and temperature program measured the curie temperature of alemepyr.
TABLE 2 temperature program for Avermel and indium testing
| Step (ii) of | Starting temperature (. degree.C.) | End temperature (. degree.C.) | Rate of temperature rise (. degree. C./min) |
| 1- |
100 | / | / |
| 2- |
100 | 250 | 10 |
The curie temperature of the alemter alloy can be calculated by equation 1:
Ts,c,Alumel＝T0,c,Alumel+Ts,M,In-T0,M,In… … equation 1
In the formula: t iss,c,Alumel-the Curie temperature modification of Altemeaux alloy, ° C; t is0,c,Alumel-the aleumel curie temperature instrumental test value, deg.c; t is0,M,In-the instrumental value of the melting point of indium, deg.c, of the standard substance; t iss,M,In-the certification nominal melting point, deg.c, of the standard substance indium;
(3) method accuracy verification
In order to verify the accuracy of the method, the method is adopted to verify two sets of standard substances of China measurement science research institute (hereinafter referred to as Chinese measurement institute) and TA company, the result is shown in Table 3, and the result shows that the Curie temperature of each standard substance tested by the Curie temperature testing method is accurate and the Curie temperature testing method is feasible.
Table 3 method verification results
Example 1
The standard substance of the alloy is prepared by the following method:
selecting raw materials: taking commercially available Altemel alloy as a raw material, such as Altemel alloy sold by Omega company, which is in a shape of a long strip, and testing the components and the content of the Altemel alloy by using an X-ray fluorescence spectrometer and a plasma emission spectrometer (ICP), the Altemel alloy raw material is mainly composed of nickel, manganese, aluminum and silicon, wherein Ni is about 95%, Al is about 2%, Mn is about 1% and Si is about 2%;
purification of raw materials: in order to reduce the content of manganese and aluminum in the raw materials, according to different boiling points and saturated vapor pressures of nickel, manganese, aluminum and silicon elements, vacuum distillation is adopted to reduce the content of impurities, and the raw materials are purified; keeping the temperature for 2.5h at 1873K for the iron component, and setting the vacuum degree at 6 Pa;
obtaining candidate standard substances: carrying out uniformity initial inspection on Curie temperatures of purified Aleamer alloy raw materials, randomly selecting 3 raw materials which are respectively numbered as 1, 2 and 3, respectively shearing a small section from head to tail, respectively representing the head and the tail by A, B, namely 1-A, 1-B, 2-A, 2-B, 3-A and 3-B, and testing the Curie temperatures of the small sections to confirm the uniformity of different parts of the alloy in the same batch; the test results are reported in table 4.
Table 4 initial uniformity data for the alexandrite alloy raw material after purification in example 1
The uniformity initial check of the purified raw material is carried out according to the analysis of variance method by using the data information in table 4, and the calculation result shows that the raw material purified in example 1 can be used as a candidate standard substance through the uniformity initial check, the raw material is cut into fine particles, the mass of each particle is about 10mg, the fine particles are subpackaged in brown glass sample bottles, the bottling amount of each bottle is about 200mg, 200 bottles are subpackaged at a time, the raw material is stored at normal temperature, and the appearance form is shown in fig. 2.
Whether the candidate standard substance is a standard substance or not is also subjected to the following series of tests and evaluations.
First, analysis of candidate standard substance components
Carrying out element composition and content test on the purified alexandrite alloy raw material, and comparing the element composition and content test with the existing alexandrite alloy standard substance of China measurement institute and TA company; wherein, the Curie point of the Altemel (GBW13239) of the Chinese metropolis is 153.8 ℃, and the uncertainty is 0.8 ℃; altemel (CRM6-40211) by TA has a Curie point of 152.6 ℃ and an uncertainty of 2.0 ℃.
The element composition and content test method is as follows: cutting small blocks at different parts of the same alloy block by using an X-ray fluorescence spectrometer (EDX, SHIMUZU) and ICP (EOS710, Agilent), carrying out parallel test for 3 times, and taking an average value as an element content test result, wherein the measurement results are shown in tables 5 and 6.
TABLE 5 comparison of the results of measuring the elements of Albemol alloy by X-ray fluorescence spectrometer
TABLE 6 comparison of the results of ICP-OES measurement of various elements of Altemel alloy
According to the results shown in tables 5 and 6, the main components of the alloys of example 1 are nickel, manganese, aluminum and silicon, and compared with the curie point standard substance of the existing alloys of example 1, the compositions of the alloys of example 1 have slight differences, but the slight differences in the compositions have larger influence on the magnetic performance, thereby causing a significant difference in the curie temperature, and the influence of each component and impurity on the curie temperature is synergistic and non-single influence, because the magnetic performance of the high nickel soft magnetic alloy is closely related to the structural state and the components of the alloy, and the difference in the magnetic performance of the alloy directly influences the curie temperature, which is shown in the following concrete:
the alloy with low initial permeability has wider distribution range of Ni content and higher Ni content, while the alloy with high initial permeability has more concentrated distribution of Ni content and relatively lower Ni content;
mn also has obvious influence on the structure of the alloy, and when the purity of the alloy is low, excessive Mn can damage the structure and generate adverse influence on the magnetic property; when the purity of the alloy is high, the texture can be improved and the magnetic property can be improved due to the high Mn content;
the effect of aluminum is similar to that of silicon, and the aluminum can reduce a phase region, coarsen crystal grains, improve resistivity, reduce a magnetic anisotropy constant K, reduce iron loss and reduce magnetic induction; when the content of aluminum is low, the aluminum and nitrogen are combined to form fine Al-N which obviously hinders grain growth during annealing and obviously reduces the magnetic performance; when the aluminum content is higher, the size of a precipitated phase Al-N is larger, which is beneficial to coarsening of crystal grains;
because silicon is a non-magnetic element, the saturation magnetization is reduced due to the high content of Si, and the magnetic induction is correspondingly reduced; si obviously hinders the mobility of crystal boundaries in the recrystallization process, and the orientation difference between crystal grains is caused when the crystal boundaries migrate at a low speed; the relative influence on the grain boundary mobility is large, the selective growth among crystal grains in the recrystallization annealing process is promoted, and the magnetic performance is not good;
in the nonmetallic inclusions, Mn and Si were added in an excessive amount as deoxidizers, and A1 was added in an excessive amount as a heat generating agent. The excessive non-metallic inclusions mainly containing non-metals such as corundum or ferromanganese ferrite are caused, and the inclusions are non-magnetic or weakly magnetic substances, so that the magnetic performance is deteriorated. Impurities such as carbon, sulfur, nitrogen, and oxygen in the alloy are particularly detrimental to magnetic properties because they distort the lattice and are difficult to magnetize.
It can be seen that the slight difference in the composition of the alemter alloy has a large influence on the magnetic properties, resulting in a significant difference in the curie temperature, and the influence of each component and impurity on the curie temperature is synergistic and not a single influence.
Second, Curie temperature uniformity detection of candidate standard substance obtained in example 1
The method is characterized in that whether the measured values of each group have systematic differences is judged by comparing the variance between the groups and the variance in the groups, if the ratio of the measured values to the variance in the groups is smaller than the critical value of the statistical test, the sample is considered to be uniform, and the specific uniformity test and result analysis are as follows:
1. experimental methods
Referring to the standard substance specification, 11 bottles of samples were randomly sampled from 200 bottles of candidate standard substances dispensed in example 1 according to the serial numbers of head, tail and middle, and 3 sub-samples were randomly sampled from each bottle of samples (i.e., 3 independent slices were arbitrarily cut), and the curie temperature of each sub-sample was measured.
And (3) obtaining 11 groups of data according to experiments, carrying out in-bottle and inter-bottle uniformity tests, and evaluating by using an F test method, namely judging whether the measured values of each group have system deviation or not by comparing the variance between the groups and the variance in the groups, namely a variance analysis method.
According to the general principle and statistical principle of standard substance definite value of JJF1343-2012, the uniformity variance analysis method adopts the following calculation method:
is provided with
Sum of variance between groups
Within group variance and
ν1m-1 … … equation 6
ν2N-m … … equation 7
Variance between groups
Variance in group
As statistic F:
the statistic is a degree of freedom (v)1、v2) F distribution variable of (2).
According to degree of freedom (v)1、v2) And given significance level α, the critical F can be found from the F distribution threshold tableαThe value is obtained. If the F value satisfies F < FαAnd then, the data groups are considered to have no obvious difference, and the samples are uniform.
2. Uniformity test
Preparation of candidate Standard substance Asbemele alloy prepared in example 1The results of the uniformity measurement data are shown in Table 7, the uniformity is checked by the variance analysis method, and Q is calculated according to the formulas 2 to 101、Q2、v1、v2、s1 2、s2 2F values are shown in Table 8.
TABLE 7 homogeneity evaluation measurement data for candidate standard substances
TABLE 8 analysis of variance for homogeneity evaluation of candidate standards (ANOVA Table)
As can be seen from the data in Table 8, the results of the homogeneity and variance analyses for the candidate standards prepared in example 1 are all F < FαThe data groups are considered to have no obvious difference, which indicates that the candidate standard substance alexandrite is uniform.
As can be seen from the calculations: all of the statistical quantities F of the candidate alexandrite standard substances prepared in example 1 were less than the homogeneity test critical value F0.05The candidate alexandrite standard substance was proved to be homogeneous.
Thirdly, detecting the stability of the Curie point standard substance of the candidate Albemeier alloy
1. Experimental methods
The stability of a standard substance is a change over time in a characteristic quantity of a specified value, and the stability of a standard substance is affected by physical, chemical, storage conditions and other factors, and it is necessary to determine a relative stability period by periodically examining the stability for a long time by an analytical method with high precision.
The stability of a standard substance includes both long term stability, which refers to the stability of the standard substance's characteristics under specified storage conditions, and short term stability; short term stability is the stability of a standard substance during transport under transport conditions.
The aleumell standard substance is subjected to long-term stability of 24 months at normal temperature and short-term stability under 7-day simulated transportation conditions according to the standard substance technical specification and the principle of dense before and sparse after.
Specifically, the candidate alexandrite Curie point standard substances are respectively placed in an incubator at (60 +/-5) DEG C and an incubator at (60 +/-5)% RH and a refrigerator at (-4 +/-1) DEG C and stored for one week to detect the short-term stability; the candidate standard substance was stored for 24 months under normal temperature storage conditions to examine long-term stability.
The stability study test method is the same as the uniformity test method, and comparison measurement is carried out in time intervals. According to the technical specification of standard substances, respectively randomly extracting 3 bottles of samples from the developed candidate Albemeier alloy standard substances according to head, tail and middle numbers each time, adopting a synchronous thermal analyzer, repeatedly measuring the samples for 3 times for each bottle of samples according to the determined Curie temperature measuring method, taking an average value, and evaluating by a regression analysis method.
2. Long term stability test
The results of the long term stability experiments for the candidate standard materials are shown in Table 9.
TABLE 9 Long-term stability test results for candidate standard substances
Since no physical/chemical model can truly describe the degradation mechanism of the candidate standard sample, a straight line is used as an empirical model:
Y＝β0+β1x … … formula 11
In the formula β0、β1As a regression coefficient, X is time, and Y is a characteristic value of a standard substance candidate.
The regression parameters were calculated as follows:
the slope is calculated from equation 12:
in the formula: xiIs the ith time point; y isiIs the observed value of the ith time point;
average value of all time points;
the average of all observations.
Intercept is represented by the formula
And (4) calculating.
β1Standard deviation s (β)1) Can be represented by formula
The calculation is carried out according to the calculation,
wherein s is the standard deviation of each point on the straight line according to the formula
The calculation is carried out according to the calculation,
in the formula XiIs the ith time point; y isiAs observed at the ith time point β0、β1Is a regression coefficient, and n is the number of measurements.
If | β1|＜t0.05,n-2·s(β1) The slope is shown to be insignificant, i.e. no instability is observed. Under the condition that the degree of freedom n-2 is 9 and the confidence level p is 0.95, the table is looked up to obtain t0.05,9＝2.26。
The stability test data of the candidate standard substances of Table 9 were subjected to regression analysis according to equation 11, and the results of the regression analysis are shown in Table 10.
TABLE 10 results of regression analysis of stability test data for the candidate standard substances of Table 9
For candidate standard substances, t0.05,n-2·s(β1)＝t0.05,9·s(β1)＝2.26×0.036＝8.14×10-2，|β1|＝5.6×10-2，|β1|＜t0.05,9·s(β1) Thus, no instability was observed.
Meanwhile, as shown in fig. 3, it can be seen from the graph of the stability results of the candidate standard substance with respect to time that there is no significant tendency of the curie temperature of the candidate standard substance to increase or decrease.
Therefore, the candidate standard substance quality value prepared in example 1 has no obvious trend change, and the preparation method and the storage condition adopted by the invention can effectively ensure the stability of the quality value.
3. Short term stability test
Considering the southern hot humid weather and the northern cold weather, and the time limit of transportation, the candidate standard substances were stored in an incubator at (60 + -5) ° c, (60 + -5)% RH, and a refrigerator at (-4 + -1) ° c, respectively, and stored for one week while being subjected to the curie temperature test every day. The results of the short term stability experiments for the candidate standard materials are shown in tables 11 and 12.
TABLE 11 short term stability test data ((60. + -. 5). degree.C.) for candidate standard substances
| Name (R) | |
|
|
|
|
| Allemel alloy | 161.36 | 161.08 | 161.38 | 161.47 | 161.51 |
TABLE 12 short term stability test data ((4. + -. 1). degree.C.) for candidate standard substances
| Name (R) | |
|
|
|
|
| Allemel alloy | 161.26 | 161.24 | 161.45 | 161.40 | 161.39 |
Similarly, | β was calculated by regression analysis of the data in tables 11 and 12 using the same analysis method as for long-term stability1|＜t0.95,n-2·s(β1). Namely, the candidate standard substance has no significant change in characteristics under simulated transportation conditions, and maintains good stability, as shown in fig. 4 and 5.
Four, constant value
1. Multi-laboratory collaborative valuation
LGC melting point standard substance is used as external standard, and 8 laboratories are combined to carry out cooperative setting on candidate standard substance, and the models of the combined laboratories and instruments are shown in Table 13.
TABLE 13 Combined laboratory and Instrument models
Before being used, each laboratory instrument is qualified by the verification of a legal metering mechanism, and the Curie temperature testing process is traced to the LGC melting point standard substance. Randomly drawn 3 sample packages from all samples were distributed to each laboratory, 3 subsamples were randomly taken from each bottle by each laboratory, the test was repeated 3 times for each subsample, the average was taken as a result, and the 8 laboratory-rated test results are listed in table 14.
TABLE 14 candidate Standard substance combination fixed value Experimental data
2. Statistical analysis of constant value data (1) analysis of suspect values within a group
And (3) receiving three subsamples of the candidate standard substance in all laboratories, repeatedly measuring each subsample for three times, calculating to obtain a corrected Curie temperature value by tracing to the melting point standard substance, and firstly examining the data of each laboratory to judge whether a suspicious value exists or not, wherein the result is shown in a table 14.
The judging method comprises the following steps: the standard deviation of the data for each laboratory was calculated and listed in table 15, and the suspect value analysis was performed using the dixon criterion and the grubbs criterion, taking the 6 th laboratory as an example, and the specific analysis process was as follows.
① using Dixon criterion for discrimination
Analysis of 6 th laboratory on the anagmaire results using the dixon criterion ranged from small to large:
160.90<161.12<161.31≤161.57<161.64<161.69<162.32<162.42<162.45
when n is 9, then
r9＞r1，r9< D (a, n), look-up table shows that D (0.05,9) ═ 0.564,
indicating that the group has no abnormal value.
② are judged by Grubbs
Also taking the result of the 6 th laboratory on alemepar as an example,
arithmetic mean value:
calculating the standard deviation of the experiment: when the s is equal to 0.57,
search for the threshold of the gridbus criterion: g (0.05,9) ═ 2.215,
thus, no abnormal value was indicated.
Similarly, no abnormal value was found in the same analysis in the other 7 laboratories. The specific calculation results are shown in table 15.
TABLE 15 analysis results of suspicious values of joint fixed value experimental data of laboratories
(2) Equal precision test
Judging the constant value data of the 8 laboratories by adopting a Kokring criterion, firstly carrying out statistical analysis on the data of each laboratory, calculating the standard deviation of each laboratory, calculating the statistic according to the Kokring criterion and the following formula, and listing the calculation results of each laboratory in a table 16:
looking up the table to obtain C (0.05,8,9) ═ 0.3043, then C < C (0.05,8,9)
TABLE 16 results of equal-precision analysis of candidate alexandrite standard substance in eight laboratories
Therefore, 8 laboratories rated the candidate alexandrite standard substance to equal accuracy.
(3) Analysis of values of suspicion between groups
The mean values for each laboratory were calculated from table 14, listed in table 17, and the suspect value analysis was performed for each mean value:
TABLE 17 mean results of the evaluation of candidate Standard substances in eight laboratories
① using Dixon criterion for discrimination
The above data were analyzed using the Dixon (Dixon) criterion, according to the mean analysis of 8 laboratory-rated results, in small to large order: 160.35<160.96<161.09<161.42<161.62<161.71<161.88<162.01, wherein n is 8
r1＞r8，r1< D (a, n), look-up table shows that D (0.05,8) ═ 0.608,
indicating that the data is abnormal.
② are judged by Grubbs
The average results of the values of aleumel in 8 laboratories were calculated as follows:
arithmetic mean value:
calculating the standard deviation of the experiment: when the s is equal to 0.53,
search for the threshold of the gridbus criterion: g (0.05,8) ═ 2.126,
thus, no abnormal value was indicated.
(4) Normal distribution test
Firstly, the data of 8 laboratories and the average value of each laboratory are subjected to normality test by adopting minitab software, the test results are respectively shown in fig. 6 and 7, and it can be known that the p values are all larger than 0.05, which indicates that the data obey normal distribution.
3. Final definite value data
The results of the joint assessments were taken as the overall mean of 8 laboratories, which was as follows:
fifth, uncertainty assessment
1. Uncertainty analysis of candidate standard substance
According to the development process of the Agomel Curie temperature standard substance, the uncertainty component of the substance mainly comprises three parts: introduction of uncertainty component u in fixed valuecharUniformity-generated uncertainty ubbAnd uncertainty u due to instabilitys。
(1) Uncertainty component u introduced in fixed valuechar
According to the method of valuing, the sources of uncertainty introduced in this section are mainly: class A uncertainty u introduced by fixed value repeatability in 8 laboratoriesAB-type uncertainty component u introduced by melting point standard substance used in constant valueB。
① 8 laboratory fixed value repeatability introduced uncertainty uA
Through statistical analysis of 8 laboratory constant value data, each data is obtained to be normal distribution, and each laboratory result is equal precision, then the standard uncertainty of the total average value of the constant value results, namely:
② LGC2601-In melting point standard substance-introduced uncertainty component uB
LGC2601-In melting point standard substance certificate with nominal melting point m (In) of 156.60 ℃ and extended uncertainty of 0.03 ℃ (k 2), thus standard uncertainty uB＝u[M(In)]＝0.03/2＝0.015℃。
③ Total uncertainty introduced by constant value of synthesized Aselmei Curie temperature standard
(2) Unevenly introduced uncertainty component ubb
The heterogeneity of standard substances is mainly due to uncertainties introduced by sample preparation, dispensing and detection. According to the general principle and the statistical principle of the fixed value of the JJF1343-2012 standard substance, the method
The uncertainty component due to inter-bottle uniformity is represented by
Is obtained, wherein sbbThe standard deviation between the bottles is shown as the standard deviation,
is the variance between the groups and is the mean variance between the groups,
is the intra-group variance, and n is the intra-group measurement times; when in use
The uncertainty component due to inter-bottle uniformity is represented by
To obtain in the formula sbbThe standard deviation between the bottles is shown as the standard deviation,
for measurement of repeatability variance in the assessment of uniformity between bottles,
is composed of
The degree of freedom of (c).
The experimental data for homogeneity are shown in table 7, and the results of the anova analysis of homogeneity evaluation of candidate alembite standard materials are shown in table 8.
Standard deviation of uniformity between bottles:
method standard deviation of measurements:
according to the calculation results, the repeatability standard deviation of the method is larger than the uniformity standard deviation between bottles, sr＞sbbThe heterogeneity of the standard introduced uncertainty:
(3) instability induced uncertainty component us
The experimental data of the long-term stability are shown in Table 9, and from the analysis of variance in the regression analysis results shown in Table 10, it can be seen that sb,1(β1) The uncertainty contribution u of the long-term stability with a validity period t of 24 months is determined by analytical stability method at 0.036 deg.Cs,1＝sb,1(β1)·X1＝0.036×24＝0.864℃。
The short term stability test data are shown in tables 11 and 12, and the standard deviation is calculated as sb,2(β2)＝0.030℃，sb,3(β3) When 0.017 ℃, the uncertainty contribution to the short-term stability for 7 days at the two temperatures is:
us,2＝sb,2(β2)·X2＝0.030×7＝0.210℃
us,3＝sb,3(β3)·X2＝0.017×7＝0.120℃
thus, the uncertainty component due to stability is:
sb,1(β1) Standard deviation for long term stability of candidate standard substance; u. ofs,1An uncertainty component for long term stability of the candidate standard substance; sb,2(β2) Is the standard deviation of short-term stability of the candidate standard substance at 60 ℃; u. ofs,2Is uncertainty component of short-term stability of candidate standard substance at 60 ℃; sb,3(β3) Is the standard deviation of short-term stability of the candidate standard substance at 60 ℃; u. ofs,3Is the uncertainty component of short-term stability at 4 ℃ for the candidate standard substance.
2. Total uncertainty of synthesis
Therefore, the expansion uncertainty U is k · UGeneral assembly＝2×0.926＝1.85℃≈2.0℃。
The above detection and analysis show that the candidate standard substance prepared in example 1 can be used as a standard substance.
Comparison of similar standard substances at home and abroad
At present, the proven standard substance related to the Curie temperature of the ferromagnetic material at home and abroad is GBW13239 developed by Chinese measurement institute, and the temperature range is 153 ℃. Each large instrument company is provided with corresponding debugging standard substances, the characteristic quantity values are widely distributed but have no traceability, and table 18 lists the comparison results of the characteristic quantity values of the national measurement institute GBW13239 and the alexanglie alloy standard substance prepared in example 1.
TABLE 18 comparison table of Curie temperature similar standard substance conditions of Altemel alloy
The standard substance of the Curie point of GBW13239 Alemel alloy of China metrological scientific research institute and the standard substance developed by the invention are compared and analyzed. The specific method comprises the following steps: the alemeprol standard substance of the present invention was measured after calibrating the instrument using the chinese institute for metrology GBW13239, and the results are shown in table 19.
TABLE 19 comparison of Curie temperature standard substance of ferromagnetic material with domestic and foreign standard substances
As can be seen from Table 19, the measured values of the standard substances all fall within the uncertainty range of the fixed value, so that the value of the Avermel alloy which is the Curie point standard substance developed by the invention is accurate, and has the characteristics of stability and convenience.
In conclusion, the standard substance of the Curie point of the Alaemalloy obtained by the preparation method of the invention gives a synthetic result of the uncertainty in the whole measurement process after analyzing the uniformity, the measurement dispersibility and uncertainty components introduced by other factors; statistical analysis is carried out on the uniformity experiment result, and the uniformity of the uniformity is in accordance with the F test and the technical specification of standard substances; a simultaneous stability study demonstrated that the developed standard was stable for 24 months.
The Curie temperature is determined to be 161.4 ℃, and the expansion uncertainty is 2.0 ℃;
finally, the obtained standard substance and similar standard substances at home and abroad are subjected to comparison experiments, and the results show that the measurement results of the standard substance and the similar standard substances at home and abroad are consistent within an uncertainty range, and the method is stable, convenient and applicable to the measurement of samples.
What has been described above are merely some embodiments of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the inventive concept thereof, and these changes and modifications can be made without departing from the spirit and scope of the invention.
Claims (10)
1. The preparation method of the standard substance of the Curie point of the Allimel alloy is characterized by comprising the following steps:
analyzing and confirming the components and the content of the raw material by using the alemter alloy as the raw material, and purifying the raw material by adopting a vacuum distillation method according to different boiling points and saturated vapor pressures of the components;
carrying out uniformity initial detection on the purified raw materials with a specific quantitative value, and screening out the raw materials with uniform Curie temperature as candidate standard substances;
and (3) carrying out uniformity inspection, stability inspection, quantity value determination and uncertainty analysis on the candidate standard substance according to the metrological requirements, and if the uniformity, the stability and the uncertainty meet the requirements, the quantity value is accurate and stable and meets the metrological characteristics, namely the Asherman point standard substance.
2. The method according to claim 1, wherein the vacuum distillation is carried out at a temperature of 1873K for 2-3h with a vacuum level set at 3-9 Pa.
3. The method of claim 2, wherein the initial uniformity test is performed by: randomly selecting at least 3 parts of raw materials, shearing at least 2 different parts of each part of raw materials, measuring the Curie temperature of the sheared part, and judging whether the materials are uniform or not according to the measurement result.
4. The method according to any one of claims 1 to 3, wherein the step of performing the homogeneity test on the candidate standard substance comprises the steps of: randomly extracting not less than 11 bottles of samples from the candidate standard substances which are divided and numbered, and randomly extracting 3 subsamples from each bottle of samples; and measuring the Curie temperature of each subsample, and comparing the variance between groups with the variance in groups to judge whether the measured values of each group have systematic differences so as to confirm whether the candidate standard substance is uniform.
5. The method of claim 4, wherein the stability test comprises a long term stability and a short term stability, the long term stability being a quantitative stability tracking a candidate standard substance for a period of 24 months at normal temperature; the short-term stability simulates high and low temperature transportation conditions, and candidate standard substances are respectively placed in an incubator at (60 +/-5) DEG C and (60 +/-5)% RH and a refrigerator at (-4 +/-1) DEG C and are respectively preserved for one week; and performing regression analysis according to the measurement result to judge whether the stability reaches the standard.
6. The method of claim 5, further comprising quantifying the Asherman Curie point standard using the LGC melting point standard as an external standard, in conjunction with 8 laboratories.
7. The method of claim 6, wherein the uncertainty analysis includes uncertainty introduced by a fixed value experiment performed on the candidate standard substance, uncertainty due to non-uniformity of the candidate standard substance, and uncertainty due to instability.
8. An alexandrite curie point standard substance obtained by the production method according to any one of claims 1 to 7.
9. The alexandrite curie point standard substance of claim 8, wherein the curie point is 161.4 ℃ and the propagation uncertainty is 2 ℃.
10. The alexandrite curie point standard substance as claimed in claim 9, wherein the alexandrite curie point standard substance comprises the following components in percentage by mass: 94.24 to 94.76 percent of Ni, 2.24 to 2.25 percent of Al, 1.23 to 1.45 percent of Mn and 1.54 to 2.29 percent of Si.
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