阅读说明：本技术 一种基于X射线粉末衍射技术的β-HMX晶型纯度检测方法 (beta-HMX crystal form purity detection method based on X-ray powder diffraction technology ) 是由 王明 潘�清 陈智群 李晓宇 栾洁玉 于 2019-09-12 设计创作，主要内容包括：本发明提出一种基于X射线粉末衍射技术的β-HMX晶型纯度检测方法,采用X射线粉末衍射技术结合化学计量学偏最小二乘法建立β-HMX晶型纯度定量校正模型及相应的晶型纯度测试方法。本发明基于多元数据分析方法,可在交叉、重叠的光谱中提取有效信息,适用于无独立特征谱峰的晶型定量分析；能在10min～15min时间内准确测定β-HMX晶型纯度,且样品用量小于50mg,检测过程无需复杂制样,安全、快捷；能够解决合成样品小试阶段、产品事故究因分析等环节中微量样品晶型纯度难以检测的问题,为β-HMX产品质量控制、生产工艺和长储过程的晶型稳定性研究提供可靠、高效的检测依据。(The invention provides a beta-HMX crystal form purity detection method based on an X-ray powder diffraction technology, which adopts the X-ray powder diffraction technology and a partial least square method of chemometrics to establish a beta-HMX crystal form purity quantitative correction model and a corresponding crystal form purity test method. The method is based on a multivariate data analysis method, can extract effective information from crossed and overlapped spectrums, and is suitable for quantitative analysis of crystal forms without independent characteristic spectrum peaks; the purity of the beta-HMX crystal form can be accurately measured within 10-15 min, the sample consumption is less than 50mg, complex sample preparation is not needed in the detection process, and the method is safe and rapid; the method can solve the problem that the purity of the crystal form of the trace sample is difficult to detect in the links of a small test stage of a synthetic sample, product accident analysis and the like, and provides a reliable and efficient detection basis for the research of the quality control of the beta-HMX product, the production process and the stability of the crystal form in the long-term storage process.)

1. a method for detecting the purity of a beta-HMX crystal form based on an X-ray powder diffraction technology combined with a chemometrics partial least square method is characterized by comprising the following steps:

S1, preparation of calibration set samples: preparing a series of beta-HMX and alpha-HMX mixed crystal samples with different component contents as calibration set samples, wherein the purity of the beta-HMX crystal is calculated according to the following formula:

In the formula: omega_βis the purity of the beta-HMX crystal form in a sample, and is expressed by percentage; m is_βWeighing the sample weight of the beta-HMX crystal form in the sample; m is_αWeighing the sample mass of the alpha-HMX crystal form in the sample;

S2, collecting X-ray powder diffraction spectrum of the correction set sample: adopting an X-ray powder diffractometer to carry out X-ray powder diffraction spectrum collection on the calibration set sample;

s3, establishing a beta-HMX crystal form purity quantitative correction model: performing spectrum pretreatment on the acquired X-ray powder diffraction spectrum, and establishing a correlation between X-ray powder diffraction and beta-HMX crystal form purity by adopting a partial least square method to obtain a beta-HMX crystal form purity quantitative correction model;

S4, detecting the crystal form purity of the sample to be detected: and detecting the sample to be detected based on the beta-HMX crystal form purity quantitative correction model established in the step S3 to obtain a beta-HMX crystal form purity detection result of the sample to be detected.

2. the detection method according to claim 1, wherein in the step S1, the calibration set sample is prepared by mixing different crystal form components by wet grinding and vacuum drying.

3. The detection method according to claim 1, wherein chromatographically pure hexane is selected as the wet mixed grinding reagent in step S1.

4. the detection method as claimed in claim 1, wherein in step S2, about 50mg of single calibration set sample is weighed and flatly laid in the groove of the sample plate dedicated for X-ray diffraction, the sample plate with the laid sample is placed in an X-ray powder diffractometer for sample spectrum collection, CuKa ray is used as diffraction source,the working voltage is 40kv, the working current is 40mA, the scanning angle range is 5-90 degrees, and the step size is 0.02 degree.

5. The detecting method according to claim 1, wherein in step S3, a quantitative calibration model of β -HMX crystal purity is established by a chemometric method, and the detecting of β -HMX crystal purity is performed on the sample to be detected based on the model.

6. The detection method according to claim 1, wherein in the step S3, the spectrum preprocessing method includes vector normalization, min-max normalization, and multivariate scatter correction.

Technical Field

the invention belongs to the technical field of explosives and powders, and particularly relates to a beta-HMX crystal form purity detection method based on an X-ray powder diffraction technology combined with a chemometrics partial least square method.

Background

The OktoAu (HMX) is an explosive with high density, high energy, low sensitivity and excellent comprehensive performance in the existing single-substance explosives, and is widely applied to the type loading in the fields of high-energy mixed explosives, solid propellants, propellant powder and the like. HMX has four crystal forms of alpha, beta, gamma and delta, and an HMX terminal product prepared by synthesizing by taking 3, 7-dinitro-1, 3,5, 7-tetraazabicyclo [3,3,1] nonane (DPT) as an intermediate has two crystal forms of alpha-HMX and beta-HMX, wherein the beta-HMX has low sensitivity and high energy and is a practical crystal form with excellent performance, and the alpha-HMX is an impurity crystal form. In order to control the quality of HMX products, a test method for the purity of the beta-HMX crystal form needs to be established; in addition, the crystal form purity detection of the beta-HMX has important significance and value for crystal form stability research in the technical process and long storage process of explosives and corresponding safety and reliability research of weapon ammunition.

The crystal form quantitative method of the homogeneous heterocrystal comprises an X-ray powder diffraction method (XRD), a Raman spectrum method, a mid-infrared/near-infrared spectrum method, a terahertz spectrum method, a solid nuclear magnetic resonance method, a differential scanning calorimetry method and the like, and the methods are more applied to the quantitative analysis of the crystal form of the medicine and are not popularized in the field of explosives and powders. In recent years, researchers establish a beta-HMX crystal form purity detection method by adopting a near infrared spectroscopy, the method is only suitable for sample detection with the sample amount larger than 5g, and the method has certain limitation on the detection of the crystal form purity of a trace sample in the links of a synthesis sample lab-scale stage, product accident cause analysis and the like; in addition, due to the sensitivity of explosive materials to external stimuli such as friction, impact, heat and the like, in order to ensure the technical safety of the detection process, a detection method with less sample consumption and high safety coefficient should be selected as much as possible in the selection of the test method. The X-ray powder diffraction technology is adopted, so that the dosage of the sample is less; the light induction does not need to be in contact with the sample; the method has the advantages of no need of sample treatment, such as dilution, sample preparation and other steps, direct detection, safety, high efficiency and the like, and has remarkable advantages in quantitative detection of the crystal form of the single-substance explosive.

disclosure of Invention

Technical problem to be solved

The invention provides a beta-HMX crystal form purity detection method based on an X-ray powder diffraction technology, and aims to solve the technical problem of how to detect the crystal form purity of beta-HMX containing an alpha-HMX impurity crystal form.

(II) technical scheme

In order to solve the technical problems, the invention provides a method for detecting the purity of a beta-HMX crystal form based on an X-ray powder diffraction technology combined with a chemometric partial least square method, which comprises the following steps:

S1, preparation of calibration set samples: preparing a series of beta-HMX and alpha-HMX mixed crystal samples with different component contents as calibration set samples, wherein the purity of the beta-HMX crystal is calculated according to the following formula:

In the formula: omega_βIs the purity of the beta-HMX crystal form in a sample, and is expressed by percentage; m is_βWeighing the sample weight of the beta-HMX crystal form in the sample; m is_αWeighing the sample mass of the alpha-HMX crystal form in the sample;

S2, collecting X-ray powder diffraction spectrum of the correction set sample: adopting an X-ray powder diffractometer to carry out X-ray powder diffraction spectrum collection on the calibration set sample;

S3, establishing a beta-HMX crystal form purity quantitative correction model: performing spectrum pretreatment on the acquired X-ray powder diffraction spectrum, and establishing a correlation between X-ray powder diffraction and beta-HMX crystal form purity by adopting a partial least square method to obtain a beta-HMX crystal form purity quantitative correction model;

S4, detecting the crystal form purity of the sample to be detected: and detecting the sample to be detected based on the beta-HMX crystal form purity quantitative correction model established in the step S3 to obtain a beta-HMX crystal form purity detection result of the sample to be detected.

further, in step S1, the calibration set sample is prepared by mixing different crystal form components by wet grinding and vacuum drying.

Further, in step S1, chromatographically pure hexane is selected as the wet mixed grinding reagent.

further, in step S2, weighing about 50mg of single calibration set sample, flatly paving the sample in the groove of the sample plate special for X-ray diffraction, putting the sample plate with the paved sample into an X-ray powder diffractometer for sample spectrum collection, taking CuKa rays as a diffraction source,The working voltage is 40kv, the working current is 40mA, the scanning angle range is 5-90 degrees, and the step size is 0.02 degree.

Further, in step S3, a quantitative calibration model of β -HMX crystal purity is established by a chemometric method, and the β -HMX crystal purity of the sample to be tested is detected based on the model.

further, in step S3, the spectrum preprocessing method includes vector normalization, min-max normalization, and multivariate scatter correction.

(III) advantageous effects

The invention provides a beta-HMX crystal form purity detection method based on an X-ray powder diffraction technology, which adopts the X-ray powder diffraction technology and a partial least square method of chemometrics to establish a beta-HMX crystal form purity quantitative correction model and a corresponding crystal form purity test method.

The invention has the following advantages:

(1) The detection method is based on a multivariate data analysis method, can extract effective information from crossed and overlapped spectrums, and is suitable for quantitative analysis of crystal forms without independent characteristic spectrum peaks.

(2) The method can accurately measure the purity of the beta-HMX crystal form within 10-15 min, the sample dosage is less than 50mg, and the detection process does not need complex sample preparation and is safe and quick. The method can solve the problem that the purity of the crystal form of the trace sample is difficult to detect in the links of a small test stage of a synthetic sample, product accident analysis and the like, and provides a reliable and efficient detection basis for the research of the quality control of the beta-HMX product, the production process and the stability of the crystal form in the long-term storage process.

Drawings

FIG. 1 is a comparison of an X-ray powder diffraction spectrum and a standard spectrum of a beta-HMX sample pretreated in this example;

FIG. 2 is a comparison of the X-ray powder diffraction spectrum and the standard spectrum of the α -HMX sample pre-treated in this example.

Detailed Description

in order to make the objects, contents and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention will be made in conjunction with the accompanying drawings and examples.

The embodiment provides a beta-HMX crystal form purity detection method based on an X-ray powder diffraction technology and a chemometrics partial least square method. The method comprises the following specific steps:

S1, preparation of calibration set samples: preparing a series of (not less than 42) beta-HMX and alpha-HMX mixed crystal samples with different component contents as calibration set samples, wherein the mass of a single calibration set sample is about 200mg, the content of the beta-HMX is more than or equal to 80 percent, and the beta-HMX is more uniformly distributed in the range of 80 to 100 percent. And weighing two crystal form standard samples of beta-HMX and alpha-HMX according to the requirements of the mass of a single sample and the content of the crystal form components in the calibration set design, and accurately obtaining the standard samples of the beta-HMX and the alpha-HMX to 0.01 mg. Placing the two crystal form standard samples in the same agate mortar, transferring 5 ml-8 ml of chromatographically pure hexane, mixing and grinding for 3min, transferring to a weighing bottle with the diameter of 25mm multiplied by 25mm, and placing in a vacuum drying oven at 40 ℃ for drying for 2h for later use.

The purity of the beta-HMX crystal form is calculated according to the following formula:

In the formula: omega_βIs the purity of the beta-HMX crystal form in a sample, and is expressed by percentage; m is_βWeighing the sample weight of the beta-HMX crystal form in the sample; m is_αis the weighed mass of the alpha-HMX crystal form in the sample.

Preparation of calibration set samples:

(1) Selection of number of samples for calibration set: mean centering was used in the modeling, requiring 6(k +1) samples to participate in the modeling, where k is the number of major factors. The number of the main factors of the model established by the invention is 6, so that the number of the correction set samples is not less than 42.

(2) Regarding the selection of wet mixed grinding reagents: the selected reagent should be a non-solvent for HMX, and secondly the reagent should meet the requirements for low impurity content, short boiling range, easy volatilization, no residue in the crystals, etc., so chromatographically pure hexane is selected as the wet mixing grinding reagent.

(3) Selection for the mixing mill: the grinding time is selected according to the test condition determined by observing the mixing uniformity of black and white solid powder after mixing and grinding for 1min, 2min and 3min under the same sample amount and test condition. Through visual observation, the black powder and the white powder are basically and uniformly mixed after being mixed and ground for 3min, so that the 3min mixing and grinding test condition is selected in the preparation process of the calibration set sample.

(4) Regarding the selection of the treatment mode after the mixed grinding: for the drying of the low-boiling residual solvent, a vacuum drying oven at 40 ℃ is generally used for drying for 2 h. The invention refers to the traditional method and uses the X-ray powder diffraction method to track and observe the change of the chemical structure and the crystal structure of beta-HMX and alpha-HMX after wet mixing, grinding and drying. As can be seen from fig. 1 and 2, the spectrums of the pretreated β -HMX and α -HMX samples are consistent with the standard spectrum, and no generation and shift of the spectrum peak occurs, indicating that no crystal transformation and thermal decomposition occur in the two crystal samples in this process, and the wet mixing grinding and vacuum drying are feasible as a method for preparing the mixed crystal sample.

And S2, collecting the X-ray powder diffraction spectrum of the correction set sample. Weighing 50mg of single calibration set sample, flatly paving the sample in a groove of a special sample plate for X-ray diffraction, putting the sample plate with the paved sample into an X-ray powder diffractometer for carrying out spectrum collection of the sample, and using CuKa raysIs a diffraction source; the working voltage is 40kv, the working current is 40mA, the scanning angle (2 theta) range is 5-90 degrees, and the step size is 0.02 degree.

s3, establishing a beta-HMX crystal form purity quantitative correction model: for the X-ray diffraction spectrum collected in step S2Performing spectrum pretreatment, performing multiple linear regression on the pretreated spectrum data and the beta-HMX crystal form purity data by adopting a partial least square method, eliminating abnormal value optimization models, establishing a series of quantitative correction models, and determining coefficients (R) by evaluating parameters²) And sequencing the advantages and the disadvantages of the established models by means of interactive validation standard deviation (RMSECV), and selecting the optimal model as a beta-HMX crystal form purity quantitative correction model.

establishing a quantitative correction model for the purity of the beta-HMX crystal form:

(1) chemometric software is required for this step.

(2) The spectrum preprocessing method comprises vector normalization, minimum-maximum normalization, multivariate scattering correction and the like.

(3) The closer the model evaluation parameter R2 is to 1, the better the model fitting effect is; the smaller the RMSECV, the higher the prediction precision and accuracy of the model, and the better the prediction effect.

(4) the beta-HMX crystal form purity quantitative correction model established by the invention is a partial least squares regression model established by adopting a vector normalization pretreatment method when the number of main factors is 6.

S4, detecting the crystal form purity of the sample to be detected: and detecting the sample to be detected based on the beta-HMX crystal form purity quantitative correction model established in the step S3 to obtain a beta-HMX crystal form purity detection result of the sample to be detected.