Method for determining impurity content in zirconia

Abstract

The present invention relates to a method for determining impurity elements in zirconia, and in particular to a method for determining impurity elements in high-purity zirconia by direct current glow discharge mass spectrometry. The method satisfies the requirements of modern high-purity material analysis and testing for reliability, accuracy and rapid multi-element analysis.

Description

Method for determining impurity content in zirconium oxide Technical Field

[0001] This invention relates to a method for determining impurity elements in zirconium oxide, and more particularly to a method for determining impurity elements in high-purity zirconium oxide by direct current glow discharge mass spectrometry. Background Technology

[0002] Zirconia, with its high melting point, wear resistance, and corrosion resistance, is an excellent functional and structural material widely used in aerospace, nuclear energy, and fiber optic communications. The performance and applications of zirconium oxide are closely related to its impurity content, and its chemical composition directly affects its properties. Currently, the main goal of my country's zirconium industry development is to meet both civilian and high-purity zirconium needs, and to establish a testing, evaluation, and quality assurance system for high-purity zirconium materials.

[0003] Currently, the main methods for analyzing the chemical composition of zirconium oxide include gravimetric analysis, spectrophotometry, atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry (ICP-AES), and ICP-AES mass spectrometry. These methods are time-consuming, involve complex steps, and require numerous chemical reagents. Among current analytical methods, the mandelic acid gravimetric method is used to determine the major element content of zirconium and zirconium alloys, with a determination range of 75%-99%. This method cannot meet purity requirements. Analysis of high-purity zirconium oxide (above 99.99%) is time-consuming. For other impurity elements, spectrophotometry, atomic absorption spectrometry, and ICP-AES have low determination efficiency and high detection limits, failing to meet the needs of high-purity material testing and analysis. ICP-AES mass spectrometry uses microwave digestion to dissolve samples, which can meet the needs of high-purity material testing and analysis, but the digestion requirements are high, and the entire analysis takes approximately three days.

[0004] The analysis of impurities in high-purity materials faces two main challenges: first, the low concentration of impurities necessitates instruments with high detection capabilities, background control, and interference elimination; second, the high concentration of matrix elements easily interferes with the analyte. Glow discharge mass spectrometry (GDMS) detection equipment, such as GDMS double-focusing high-resolution mass spectrometers, features low detection limits, wide linear ranges, and simultaneous multi-element determination, making it suitable for macro, micro, trace, and ultra-trace analysis. Currently, the use of glow discharge mass spectrometry to analyze trace impurities in samples has mature experience, and analytical standards have been established for materials such as high-purity copper, high-purity titanium, and high-purity aluminum.

[0005] In their paper "Determination of 36 Trace Impurity Elements in High-Purity Zirconium by Glow Discharge Mass Spectrometry" (Metallurgical Analysis, 2019, 39(5):13-18), Mo Shumin et al. established an analytical method for determining 36 trace impurity elements, including Na, Al, Si, P, Ti, V, Cr, and Fe, in high-purity zirconium by GDMS and used this method to determine the trace impurity elements in high-purity zirconium samples. Summary of the Invention

[0006] The purpose of this invention is to provide a method for rapidly, reliably, and accurately determining impurity elements in high-purity zirconium oxide.

[0007] The objective is achieved by a method for determining impurity elements in high-purity zirconium oxide using direct current glow discharge mass spectrometry, the method comprising:

[0008] 1) High-purity zirconium oxide is pretreated to obtain the sample to be tested;

[0009] 2) Pre-sputter the sample to be tested;

[0010] 3) Select zirconium and hafnium as the matrix, and set the isotopes and resolution of the elements to be measured;

[0011] 4) Perform DC glow discharge mass spectrometry analysis; and

[0012] 5) The sum of the signals generated by zirconium and hafnium is defined as 100%. The content of the analyte is calculated based on the ratio k of the signal intensity of the analyte to the sum of the signal intensities obtained from zirconium and hafnium. The ratio factor k is calculated according to formula ①:

[0013] Among them, M (Zr+Hf) It is the sum of the relative molecular masses of zirconium and hafnium;

[0014] It is the sum of the relative molecular masses of zirconium dioxide and hafnium dioxide. Detailed Implementation

[0015] Before describing several exemplary embodiments of the present invention, it should be understood that the invention is not limited to the details of the construction or process steps described below. The invention may have other embodiments and can be implemented or carried out in various ways.

[0016] The following definitions are provided for the terms used in this specification.

[0017] Throughout the specification, including the claims, the terms “comprising one” or “comprising one” shall be understood to be synonymous with the term “comprising at least one”, unless otherwise stated, and “between” or “to” shall be understood to include the limiting value.

[0018] The terms “a,” “an,” and “the” are used to refer to one or more (i.e., at least one) of the grammatical objects in this clause.

[0019] The term “and / or” includes the meanings “and”, “or”, and all other possible combinations of elements associated with the term.

[0020] All percentages and ratios are mentioned by weight unless otherwise stated.

[0021] The terms “mixture” or “composition” as used refer to, but are not limited to, any combination of physical or chemical forms, such as blends, solutions, suspensions, alloys, complexes, etc.

[0022] In a first aspect, the present invention relates to a method for determining impurity elements in high-purity zirconium oxide using direct current glow discharge mass spectrometry, the method comprising:

[0023] 1) High-purity zirconium oxide is pretreated to obtain the sample to be tested;

[0024] 2) Pre-sputter the sample to be tested;

[0025] 3) Select zirconium and hafnium as the matrix, and set the isotopes and resolution of the elements to be measured;

[0026] 4) Perform DC glow discharge mass spectrometry analysis; and

[0027] 5) The sum of the signals generated by zirconium and hafnium is defined as 100%. The content of the analyte is calculated based on the ratio k of the signal intensity of the analyte to the sum of the signal intensities obtained from zirconium and hafnium. The ratio factor k is calculated according to formula ①:

[0028] Among them, M (Zr+Hf) It is the sum of the relative molecular masses of zirconium and hafnium;

[0029] It is the sum of the relative molecular masses of zirconium dioxide and hafnium dioxide.

[0030] The term "high-purity zirconium oxide" refers to high-purity zirconium dioxide (ZrO2) materials, typically used in high-end applications such as electronics, optics, ceramics, catalysts, and biomedicine. High-purity zirconium oxide generally has a purity of 99.99% or higher, meaning it has extremely low impurity content, ensuring its performance and stability in specific applications.

[0031] In one embodiment of the present invention, the pretreatment includes pressing high-purity zirconium oxide powder into tablets using a tableting mold.

[0032] In one embodiment of the present invention, the tablet pressing mold includes an upper mold, a cathode block, and a lower mold.

[0033] In one specific embodiment of the present invention, the tablet compression mold structure is as described in Utility Model Patent Application No. 202421204431.5. The tablet compression mold is suitable for glow discharge mass spectrometry detection of both conductive and non-conductive powder samples, and allows for convenient demolding and recovery of the powder samples.

[0034] Utility model patent application No. 202421204431.5 provides a tableting mold, comprising:

[0035] The upper die includes a pressure head and a pressure head rod disposed above the pressure head;

[0036] The cathode block, made of conductive material, includes a pressing hole through the cathode block, the cross-sectional dimensions of which correspond to the cross-sectional dimensions of the pressing head;

[0037] The lower mold includes a pressing position and a demolding position, wherein the pressing position includes at least one pressing plane for pressing the sample, and the demolding position includes a demolding groove for receiving the sample, wherein the cross-sectional dimension of the demolding groove is smaller than the cross-sectional dimension of the cathode block;

[0038] When the tableting mold is in the tableting configuration, the cathode block is positioned at the tableting position of the lower mold, and the pressing head can pass through the tableting hole of the cathode block and abut against the tableting plane; when the tableting mold is in the demolding configuration, the cathode block is positioned at the demolding position of the lower mold, and the pressing head can pass through the tableting hole of the cathode block and extend into the demolding groove.

[0039] In a preferred embodiment of the invention, the components of the tableting mold are made of niobium or tantalum, wherein the niobium or tantalum used to manufacture the cathode block has a purity of 99.999% or higher. However, it is understood that they can be made of other materials, provided they are suitable for testing requirements.

[0040] In one specific embodiment of the present invention, the cathode block is made of niobium metal with a purity of 99.999% or higher, and the content of a single impurity element (such as lithium, boron, sodium, magnesium, aluminum, silicon, calcium, titanium, vanadium, chlorine, manganese, iron, nickel, copper, zinc, etc.) is not greater than 0.05 ppm.

[0041] In one specific embodiment of the present invention, the metal selected as the cathode block is tantalum with a purity of 99.999% or higher, and the content of individual impurity elements other than niobium (such as lithium, boron, sodium, magnesium, aluminum, silicon, calcium, titanium, vanadium, chlorine, manganese, iron, nickel, copper, zinc, etc.) is not greater than 0.05 ppm.

[0042] In one specific embodiment of the present invention, in order to avoid introducing contamination, the tableting mold is cleaned in an inorganic strong acid solution to remove surface contaminants before tableting, then rinsed with deionized water, cleaned with an organic reagent, and dried with nitrogen gas for later use.

[0043] The inorganic strong acid is selected from one or more combinations of hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, and chloric acid.

[0044] In a more preferred embodiment of the present invention, the inorganic strong acid is electronically pure (MOC) hydrofluoric acid. In another more preferred embodiment of the present invention, the inorganic strong acid is a mixture of hydrofluoric acid and nitric acid, wherein the volume ratio of hydrofluoric acid to nitric acid is 1:1 to 3:1, including 5:4, 3:2 and 2:1.

[0045] The organic reagent is selected from one or more combinations of acetone, isopropanol, methanol, ethanol, dichloromethane, carbon tetrachloride, n-hexane, cyclohexane, and chloroform.

[0046] In a preferred embodiment of the present invention, the pressing pressure for compressing the high-purity zirconium oxide is 0.1 to 0.9 tons, including 0.2, 0.3, 0.4, 0.5, 0.6, and 0.8 tons. The number of compression cycles is 2 to 8, including 3, 4, 5, 6, and 7, to compress the high-purity zirconium oxide to be tested into a flat, sheet-like sample.

[0047] In one embodiment of the present invention, the pre-sputtering discharge current is 25-50mA, including 30, 35, 40 and 45mA, preferably 35-45mA, and more preferably 40mA.

[0048] In one embodiment of the invention, the pre-sputtering discharge gas flow rate is from 400-550 mL / min, including 420, 440, 460, 480, 500 and 520 mL / min, preferably 450-500 mL / min, and more preferably 480 mL / min.

[0049] In one embodiment of the present invention, the pre-sputtering time is greater than or equal to 3 minutes, preferably greater than or equal to 5 minutes.

[0050] In one embodiment of the present invention, the analytical test includes selecting a resolution mode according to the interference of the analyte element in glow discharge mass spectrometry.

[0051] In one specific embodiment of the present invention, when collecting the analyte, the required resolution is MR > 4000 and HR > 10000. For elements with mass spectrometry interference: K, Ti, As, Se, Nb, Ir, Pt, Au, Pd, Cd, Ag, K, Ti, As, Se, Nb, Ir, Pt, and Au are tested at high resolution, while Pd is tested at lower resolution. 94 Zr 16 O, 92 Zr 16 O, 90 Zr 16 O interference, therefore this invention selects isotopes 105 Pd is tested; for Cd, there is... 94 Zr 16 O, 92 Zr 16 O, 94 Zr 16 O, 94 Zr 17 O, 96 Zr 17 O, 96 Zr 18 O, 90 Zr 16 O, therefore the present invention selects 116 Cd was tested; Ag was present. 90 Zr 17 O, 92 Zr 17 O, 91 Zr 18 O, 94 Zr 16 O interference; both isotopes are affected by oxide interference, and the interference cannot be removed by selecting different isotopes. Therefore, this invention selects... 109 Ag, and introduce interference equations for offline processing and correction: 109 Ag = 109 [I]-10.1321× 113 [I]+0.4552× 115 [I], where 109 [I] represents the mass spectral signal value measured at mass number 109, in cps (counts per second); 113 [I] is the mass spectral signal value measured at mass number 113, in cps; 115 [I] represents the mass spectral signal value measured at mass number 115, in cps.

[0052] In one embodiment of the present invention, the method further includes calculating the purity of high-purity zirconium oxide using the following formula ②:

[0053] in, The purity of high-purity zirconium oxide is expressed as the sum of the percentages of ZrO2 + HfO2 content.

[0054] C x The test content of element x, expressed in ppm.

[0055] C (x，Ta) The content of element x in high-purity niobium or tantalum, expressed in ppm.

[0056] ∑ Element The sum of the contents of all elements to be tested, expressed in ppm, minus the contents of the corresponding elements in high-purity niobium or high-purity tantalum, expressed in ppm.

[0057] This invention provides a method for rapid determination and purity assessment of impurity elements in non-conductive high-purity zirconium oxide using DC glow discharge mass spectrometry. Using high-purity metals for sample preparation simplifies cumbersome sample pretreatment steps, avoids introducing contamination, and achieves a detection limit down to the ppb level. Furthermore, by setting appropriate parameters and optimizing the method for interfering elements in mass spectrometry analysis, this invention employs a bundled approach to calculate the oxide ratio factor of zirconium-hafnium binary oxides, establishing a formula for purity calculation. This method meets the requirements of modern high-purity material analysis and testing for reliability, accuracy, and rapid multi-element analysis.

[0058] Specifically, the present invention relates to the following embodiments:

[0059] 1. A method for determining impurity elements in high-purity zirconium oxide using direct current glow discharge mass spectrometry, the method comprising:

[0060] 1) High-purity zirconium oxide is pretreated to obtain the sample to be tested;

[0061] 2) Pre-sputter the sample to be tested;

[0062] 3) Select zirconium and hafnium as the matrix, and set the isotopes and resolution of the elements to be measured;

[0063] 4) Perform DC glow discharge mass spectrometry analysis; and

[0064] 5) The sum of the signals generated by zirconium and hafnium is defined as 100%. The content of the analyte is calculated based on the ratio k of the signal intensity of the analyte to the sum of the signal intensities obtained from zirconium and hafnium. The ratio factor k is calculated according to formula ①:

[0065] Among them, M (Zr+Hf) It is the sum of the relative molecular masses of zirconium and hafnium;

[0066] It is the sum of the relative molecular masses of zirconium dioxide and hafnium dioxide.

[0067] 2. The method as described in embodiment 1, wherein the pretreatment includes pressing high-purity zirconium oxide into tablets using a tableting mold.

[0068] 3. The method as described in embodiment 2, wherein the tableting mold includes: an upper mold, a cathode block, and a lower mold.

[0069] 4. The method as described in embodiment 3, wherein each component of the tableting mold is made of niobium or tantalum metal, wherein the purity of the niobium or tantalum metal used to manufacture the cathode block is above 99.999%.

[0070] 5. The method described in Scheme 2-4, wherein the pressure applied to compress the high-purity zirconium oxide is 0.1 to 0.9 tons.

[0071] 6. The method as described in embodiments 1-5, wherein the pre-sputtering discharge current is 25-50mA.

[0072] 7. The method as described in embodiments 1-6, wherein the pre-sputtering discharge gas flow rate is from 400-550 mL / min.

[0073] 8. The method described in embodiments 1-7, wherein the pre-sputtering time is greater than or equal to 3 minutes, preferably greater than or equal to 5 minutes.

[0074] 9. The method described in Scheme 1-8, wherein the analysis and testing includes selecting a resolution mode according to the interference of the element to be measured in glow discharge mass spectrometry.

[0075] 10. The method as described in embodiments 4-9 further includes calculating the purity of high-purity zirconium oxide using the following formula ②:

[0076] in, The purity of high-purity zirconium oxide is expressed as the sum of the percentages of ZrO2 + HfO2 content.

[0077] C x The test content of element x, expressed in ppm.

[0078] C (x，Ta) The content of element x in high-purity niobium or tantalum, expressed in ppm.

[0079] ∑ Element The sum of the contents of all elements to be tested, expressed in ppm, minus the contents of the corresponding elements in high-purity niobium or high-purity tantalum, expressed in ppm.

[0080] Example

[0081] The invention is illustrated by the following examples, but they should not be construed as limiting the scope of the invention.

[0082] High-purity tantalum plates were placed in a mixed acid solution (HNO3:HF = 1:1) for reaction cleaning to remove surface contaminants. They were then rinsed with deionized water, cleaned with acetone, and dried with nitrogen. 99.99% pure zirconium oxide powder was placed into the pressing hole of a high-purity tantalum tablet mold and pressed three times at a pressure of 0.5 tons to produce flat, sheet-like samples. Six parallel tablet samples were prepared. Nitrogen gas was used to remove surface deposits from the tablet samples, which were then placed in a sample cell. An Element GD Plus glow discharge mass spectrometer was used for testing. Measurements were taken according to the parameters in Table 1, and signals of the analyte and matrix elements Zr and Hf were collected.

[0083] Table 1 Instrument Operating Parameters

[0084] Input the ratio coefficient factor of the elemental substance to the oxide calculated in formula ①. The instrument automatically determines the content of the element to be tested and subtracts the content of the corresponding impurity element in high-purity tantalum to obtain the actual content of the impurity element in high-purity zirconium oxide. To ensure the reliability of the results, six measurements were performed and the precision was statistically analyzed. In addition, a tantalum block was used as a blank sample for the determination of the detection limit. The specific results are shown in Table 2.

[0085] The verification experiment was conducted using an inductively coupled plasma mass spectrometer, and the experimental method followed the standard YS / T568.12-2022. The parameters are shown in Table 1. Verification was performed on some elements, and the results are also listed in Table 2.

[0086] Furthermore, the comparative experiment used the same sample preparation and detection procedures as the examples, the difference being that hafnium was not selected as the matrix in the comparative experiment. Measurements were performed according to the parameters in Table 1, and signals of the analyte and the matrix element Zr were collected. The measurement results are also shown in Table 2.

[0087] Table 2 Comparison of Measurement Results

[0088] Experimental results show that without hafnium as the matrix, most measurement results are too high, and the results for some impurity elements deviate significantly from those obtained by inductively coupled plasma mass spectrometry (ICP-MS), failing to accurately reflect the true values. In contrast, the method of this invention uses zirconium and hafnium as internal standards in the matrix, achieving a precision of less than 150% within the range of 0.001 to 0.1 ppm, while the precision for other orders of magnitude does not exceed 80%. Compared with the results of ICP-MS, the two methods show high consistency in measurement results of the same order of magnitude, with the results for some elements being very close.

[0089] Finally, the purity of zirconium oxide was calculated to be 99.992% using formula ②, consistent with the expected value of the sample. The entire analysis process took only one day. Compared with wet analysis and inductively coupled plasma mass spectrometry, this invention significantly shortens the analysis cycle and improves efficiency.

Claims

1. A method for determining impurity elements in high-purity zirconium oxide using direct current glow discharge mass spectrometry, the method comprising: 1) High-purity zirconium oxide is pretreated to obtain the sample to be tested; 2) Pre-sputter the sample to be tested; 3) Select zirconium and hafnium as the matrix, and set the isotopes and resolution of the elements to be measured; 4) Perform DC glow discharge mass spectrometry analysis; and 5) The sum of the signals generated by zirconium and hafnium is defined as 100%. The content of the analyte is calculated based on the ratio k of the signal intensity of the analyte to the sum of the signal intensities obtained from zirconium and hafnium. The ratio factor k is calculated according to formula ①: Among them, M (Zr+Hf) It is the sum of the relative molecular masses of zirconium and hafnium; It is the sum of the relative molecular masses of zirconium dioxide and hafnium dioxide.

2. The method of claim 1, wherein the pretreatment includes pressing high-purity zirconium oxide into tablets using a tableting mold.

3. The method of claim 2, wherein the tableting mold comprises: Upper mold, cathode block, and lower mold.

4. The method of claim 3, wherein each component of the tableting mold is made of niobium or tantalum, wherein the purity of the niobium or tantalum used to manufacture the cathode block is above 99.999%.

5. The method according to claims 2-4, wherein the pressure applied to compress the high-purity zirconium oxide is 0.1 to 0.9 tons.

6. The method according to claims 1-5, wherein the pre-sputtering discharge current is 25-50mA.

7. The method according to claims 1-6, wherein the pre-sputtering discharge gas flow rate is from 400-550 mL / min.

8. The method according to claims 1-7, wherein the pre-sputtering time is greater than or equal to 3 minutes, preferably greater than or equal to 5 minutes.

9. The method according to claims 1-8, wherein the analysis and testing includes selecting a resolution mode according to the interference of the element to be tested in glow discharge mass spectrometry.

10. The method of claims 4-9, further comprising calculating the purity of high-purity zirconium oxide using the following formula ②: in, The purity of high-purity zirconium oxide is expressed as the sum of the percentages of ZrO2 + HfO2 content. C x The test content of element x, expressed in ppm. C (x，Ta) The content of element x in high-purity niobium or tantalum, expressed in ppm. ∑ Element The sum of the contents of all elements to be tested, expressed in ppm, minus the contents of the corresponding elements in high-purity niobium or high-purity tantalum, expressed in ppm.

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