CN1037713C - Gold ornaments X-ray fluorescent detecting method - Google Patents

Abstract

The present invention relates to an X-ray fluorescence (XRF) detecting method used for measuring gold ornaments, which comprises the following steps: a calibration curve for standard samples is made in a definite condition; the XRF intensity of each element in the sample is measured; the presumptive content Xi (presumptive) and the approximate content Xi (approximate) of each element are calculated; unitary processing is carried out on the presumptive contents, and the approximate content Xi (approximate) of each element can be obtained; the standard calibration curve is converted; the believable content Xi (believable) of each element of the sample is calculated; unitary processing is also carried out on the believable content of the element to obtain the reported content value Xi (reported) of each element.

Description

The XRF method of inspection of gold ornaments

The present invention relates to a kind of method, more particularly, relate to a kind of method with XRF instrument check gold ornaments purity with XRF (XRF) check metallic article constituent content.

The gold ornaments method of inspection commonly used is test stone scarification and hydrometer method.The test stone scarification is to utilize 12 acupuncture needles of different quality and gold ornaments cut on the fine and smooth test stone of black simultaneously, and the cut color of gold ornaments just is defined as the quality of gold ornaments near the color of which root acupuncture needle cut with the quality of this root acupuncture needle.Two adjacent acupuncture needle purity of quality differ 8%.Obviously this method is too coarse, and can't differentiate gold-plated ornaments.

The ratio of precision test stone scarification height of hydrometer method, it is according to gold and the difference of specific gravity of impurity element check gold ornaments purity, and the error of this method can reduce in 1%.But this method must know in advance gold ornaments greatly to quality, otherwise error is bigger.In addition, The pretreatment is cumbersome, can't check hollow ornaments such as earrings.

The standard GB 9288-88 of gold ornaments check is a fire assaying.This method is done the subsequent collection agent with pure lead, sample is put into special porous bone ash ware oxidation ash blow.When lead oxides was absorbed by the bone ash ware, other impurity separated with gold and silver, and gold and silver is trapped in the bone ash ware, with the parting method gold is told weighing then, and method error is less than 0.03%.This method needs fine silver, reagent and materials such as pure lead, nitric acid, special bone ash ware, and the consumption of golden being damaged property of sample are finished the time of sample needs more than 8 hours, therefore discomfort is fit to do the routine analysis, and can only do the classics foundation that gold ornaments is analyzed data.

In addition, the situation of also useful emission spectrometry check gold ornaments purity, but method is lack of standardization, consumes sample, and time-consuming, cost an arm and a leg, thereby rare.

Therefore, the object of the present invention is to provide and a kind ofly check metallic article with XRF, the method for gold ornaments particularly can be quick with this method, accurately determines the constituent content in the checking matter.

At certain content range, during with the element in the xrf method working sample, the content of this element is linear in XRF signal that receiver is accepted and the sample.But because common XRF analysis requires sample to have a plane really to make reference, and gold ornaments does not have such plane thereby become its xrf method check difficult point.The present invention handles the experimental data of measuring with twice normalization method, has solved this problem.

Method step of the present invention is as follows:

(1) at the calibration curve of determining production standard sample under the condition.

Standard model can be with the standard model of being specified gold ornaments standard specimen production unit Shenyang Smeltery Factory to provide by country.The XRF intensity of each element in the difference bioassay standard sample, divide three sections related coefficients of calculating between XRF counting intensity and constituent content by the constituent content distribution range of proof gold ornaments, alloy ornament and low-grade alloy ornament, do linear regression with least square method, determine the slope (bi) and the content intercept (ci) of all segment standard calibration curves of each element.Following table has been listed above-mentioned these numerical value:

	Content distribution (%)	Correlation coefficient r	The linear relationship degree of confidence	Straight slope bi	Intercept ci
						Au	＞97	＞0.990	99％	9.458×10 -6	-120.74
55-97	＞0.990	99％	4.755×10 -6	-20.92
					＜55		0.938	95％	3.126×10 -6	0
Ag	3-30％	＞0.990	99％	1.576×10 -6							12.19
					＜3％	＞0.990	99％	2.471×10 -6	0
	Cu	30-60	＞0.990	99％						1.295×10 -6	20.81
3-30					＞0.990	99％	1.576×10 -6	12.19
		＜3	＞0.990	99％					2.471×10 -6	0
Zn					＜10	＞0.990	99％	1.311×10 -6			0

(2) the XRF intensity of each element of working sample is calculated the false content Xi (vacation) and the approximate content Xi (closely) of each element.

Sample is left intact, and directly records each element XRF intensity.Because of its area of illumination size is different with standard model, thereby directly the application standard calibration curve calculates constituent content.Here, what earlier each element of preparation comprised the sample size scope crosses initial point linear-apporximation calibration curve, and uses it and the sample XRF intensity that records is calculated element " content ".This " content " differs several times with actual content, is referred to as " false content " Xi (vacation).The false content of each element and multiple that actual content differs are approximate in the sample.Normalizing is handled these false content, just can obtain the approximate content Xi (closely) of each element.

(3) conversion standard correction slope of a curve, the credible content Xi of each element of calculation sample (can)

If the shape of standard series sample is become the same shape of gold ornaments and size with size conversion, the intercept of typical curve is constant, and slope will change.The multiple that slope changes equals the ratio of the same sample XRF intensity of shape and size conversion front and back, that is the ratio of above-mentioned approximate content Xi (closely) and false content Xi (vacation).So, primary standard calibration curve slope conversion Xi (closely)/Xi (vacation) doubly, just can be directly with record sample XRF intensity calculating constituent content Xi (can):

Xi (can) being called credible content, it has overcome the deviation of calibration curve when calculating false content and approximate content, and confidence level improves greatly.

(4) the credible content of element is done normalizing again and handle, obtain each element and quote content value Xi (newspaper)

Xi: each measures the percentage composition of element.

If equal body jewellery, Xi (newspaper) data can be offered the user.But proof gold ornaments content is quoted mode and can be reported outward by 99%, 99.9%, 99.99% or 99.999% these several specified datas.The proof gold ornaments do not contain element Ni, and element Ni is a mandatory component in the gold-plated product, and spectral line is significantly easily surveyed, thereby to select it be gold-plated product sign element.Yet the standard model box also contains small amount of N i element, forms the background spectral line in the mensuration process, should deduct.So, stipulate the K of Ni in the empty sample box _αThe XRF maximum of intensity is gold-plated product critical intensity.Gold-plated product can only be reported the gold-plated ＂ conclusion of ＂, do not report the gold content data.

The instrument of implementing the inventive method can be the above type X-ray fluorescence analyser of 3KW, adopts germanium or the atomic number plate target greater than rhodium, and light source adds filtrator, and colimated light system adopts thick slit; Analyzing crystal adopts LiF (200) without exception, main frame voltage 50kv, main frame electric current 50mA, gate time 10 seconds.

In general, the quality of the gold ornaments that the dealer and the holder of gold ornaments was concerned about can reflect with 24K, 18K, several indexs such as gold-plated, have only the 24K gold need indicate the content of gold content and each impurity element, only need provide gold content to 18K gold, and the conclusion that gold-plated ornaments only need provide the gold-plated ＂ of ＂ is got final product.Table 2 has been listed the content value (unit is %) of a typical 24K gold ornaments and a typical 18K gold ornaments.

	Au	Ni	Cu	Zn	Ag	Pt	W
								24K	99.92	0.00	0.00	0.00	0.07	0.00	0.00
18K	75.49	0.00	21．39	0.00	3.11	0.00	0.00

Usually the impurity in the gold ornaments of the above quality of 18K has only Ag, Cu, Zn and Ni, and its position of spectral line is as shown in table 3:

Element	Au	Ag	Cu	Zn	Ni
						Spectral line	L α	K α	K α	K α	K α
The 2Q angle	36.94	16.00	45.01	41.78	48.65

Example 1

Certain gold finger-ring records each element XRF intensity (Ii) and lists in the table 4:

Measure element spectral line	AuLa	AsKa	CuKa	ZnKa
					XRF intensity I i	44087	977	113	104

Start microcomputer, listed Ii in the input table 4 checks in the linear approximate correction rate of curve bi (closely) of each element in the program, and calculates the false content Xi (vacation) of each element with this, obtains the approximate content Xi (closely) of each element through the normalizing processing and lists in table 5:

Element	Au	Ag	Cu	Zn
					Bi (closely)	3.696×10 -4	1.263×10 -4	2.031×10 -4	1.428×10 -4
Xi (vacation) %	16.30	0.12	0.02	0.01
					Xi (closely) %	99.09	0.73	0.12	0.06

With Xi in the table 5 (closely), in program, check in each element standard correction rate of curve bi, with its ratio that is multiplied by Xi (closely) and Xi (vacation), promptly become practical calibration curve slope bi (reality).Each element XRF intensity I i and practical calibration curve that utilization records, calculate each element credible content Xi (can), what normalizing handle to obtain each element again quotes content Xi (newspaper), lists in the table 6:

Element	Au	Ag	Cu	Zn
					Slope of standard curve bi	3.372×10 -4	1.458×10 -4	2.419×10 -4	1.777×10 -4
Bi (reality)=Xi (closely)/Xi (vacation) * bi	2.050×10 -3	0.887×10 -3	1.451×10 -3	1.066×10 -3
					Xi (can)=bi (reality) I i+C i	99.15	0.87	0.16	0.14
Xi (newspaper)=Xi (can)/∑ Xi (can) * 100%	98.86	0.87	0.16	0.11

Programming check NiK α intensity subcritical value, thereby sample is not gold-plated product, gets Au=99% and finishes.

Claims (1)

1. an XRF method of inspection of measuring gold ornaments comprises the following steps:

(1) at the calibration curve of determining production standard sample under the condition.

The x-ray fluorescence intensity of each element in the difference bioassay standard sample, divide three sections related coefficients of calculating between XRF counting intensity and constituent content by the element distribution range of proof gold ornaments, alloy ornament and low-grade alloy ornament, do linear regression with least square method, determine the slope (bi) and the content intercept (ci) of all segment standard calibration curves of each element;

(2) x-ray fluorescence intensity of each element of working sample calculates the false content Xi (vacation) and the approximate content Xi (closely) of each element.

Sample is left intact, and directly records each element x-ray fluorescence intensity; First each element of preparation comprises the calibration curve of initial point linear-apporximation excessively of sample size scope, and use it and calculate element " false content " Xi (vacation) with the sample x-ray fluorescence intensity that records, normalizing is handled these false content, just can obtain the approximate content Xi (closely) of each element:

(3) conversion standard correction slope of a curve, the credible content Xi of each element of calculation sample (can)

(4) the credible content of element is done normalizing again and handle, obtain each element and quote content value Xi (newspaper)

Above various in, Xi is that each measures the percentage composition of element.