1、Application Background

Hunan Dongfang Scandium Industry Co., Ltd. is a high-tech enterprise specialized in new technology development and product production of rare earth scattered metal elements represented by scandium. It is a leader in scandium development. Company's business covers scandium industrial chain (including waste slag of scandium recovery, all kinds of scandium oxide, scandium, aluminum scandium metal alloy, scandium zirconium compounds and scandium ceramic electrolyte materials and other products of technology research and development and production), also in high purity rare earth metals, rare earth alloy, and other high-end material development and mastered the core technology and market-oriented production. Aluminum foam scandium alloy composite plate has been used in "CRRC", aluminum alloy welding wire and profiles containing scandium have also been promoted and applied in the market.

Our company is entrusted by Hunan Dongfang Scandium Industry Co., LTD to test the tantalum element content on scandium alloy surface. Through simple communication with the process personnel of Hunan Oriental Scandium Industry Co., LTD., the company produces high purity scandium metal. Due to the production process, tantalum is coated on the surface of scandium metal. After production, in order to obtain high purity scandium metal, the tantalum element on the surface needs to be manually polished. Before there was no instrument, the determination of whether the tantalum element was polished below the limit content was visually determined by the process personnel after years of work experience. Due to human discriminant content, there is a large error. The customer chose LANScientific TrueX handheld X-ray fluorescence spectrometer for rapid, nondestructive and accurate content analysis of samples.

2、Instrument Configuration

Mode： TrueX

X-Ray Tube： 4 w Ag Anode

Detecter： SDD Detecter

Sample Types：scandium

Film： SDI

collimator： 2.5mm

Filter： Al2000

Analysis time： 30s

Environment： Air

Tube Voltage： 40KV

Tube Current： 62uA

316 Counting rate： 58000

316 Live time： 60%

Customer sample No. 4 count rate： 29756

Customer sample No. 4 Live time： 83%

Filter： Al2000

DPP parameter setting：PeakTime：4 FlatTop：7 HWGain：1

3、Sample information

3.1 Sample Preparation

Since the sample is precious and needs to be recovered by the customer, and has been polished by the customer, our personnel do not need to carry out any pre-treatment on the sample. Directly measure the sample and make the test method. Sample photos are shown below.

3.2 Sample Content

Sample content is shown in Table 1

Species	Product number	Ta content（ppm）
Sc Alloy	1	200
Sc Alloy	2	200
Sc Alloy	3	300
Sc Alloy	4	700
Sc Alloy	5	800
Sc Alloy	6	22200

Table 1 Sample content table

4.Curve Production

4.1 Element Boundary

In order to better realize the application, the element boundary is selected, as shown in Table 2.

Element	Min	Max	Eln
Sc	3.94	4.21	Ka
Ta	9.2	9.5	Lb
Mn	5.74	6.05	Ka

Table 2 Element boundary table

4.2 The intensity of the rules

In order to better realize the application, the element strength rule is selected, as shown in Table 3.

Elements	The intensity of the rules
Sc	Net Intensity
Ta	Tatol Intensity
Mn	Net Intensity

Table 3 Element strength rules

4.3 Method

Because the sample provided by the customer is uneven and the customer cannot provide its measuring point, our technician cannot use the sample for calibration. If the customer's sample is used for calibration, first of all, it is necessary to find out the measurement point with similar content to that provided by the customer. After calibration, it is necessary to move the sample to the test point before the test is successful. Therefore, the application uses the basic parameter method, only calibrates the pure elements, does not calibrate the standard sample, and directly tests the curve after generation.

5.Data analysis results

The surface of scandium alloy provided by the customer has uneven tantalum content after artificial polishing. In addition, there are clusters of tantalum elements on the customer's reaction surface, which will also lead to uneven content. According to this, we can know that the sample provided by the customer is the sample with uneven content. Since the content provided by the customer was tested by the hand-held machine provided by us earlier, the customer could not determine the measuring point. Therefore, in the process of testing, we need to constantly move the sample to find the measuring point when the customer tests.

5.1 Instrument accuracy test

Through the test sample, the test content is compared with the content provided by the customer, the test results show that the current instrument application can fully meet the customer's measurement needs. The test results are shown in Table 4, and the linear correlation between tantalum element test results and customer results is shown in Figure 1.

Sample	Test Content（ppm）	Customer Content（ppm）
1	268.08	200
2	278.86	200
3	297.19	300
4	706.76	700
5	848.26	800
6	22633.52	22200

Table 4 Accuracy test sheet

5.2 Instrument stability test

Through the instrument, the stability of the 300ppm sample and 700ppm sample of the customer was tested for 20 times respectively. According to the average value, standard deviation and relative standard deviation obtained at last, it can be judged that the current instrument has good stability and can meet the stability requirements of the customer. Typical results are shown in Table 5, and specific results are shown in Table 6 and Table 7.

Element：Ta Unit：PPM
Sample No.	Standard Content	Average value	Standard deviation	RSD%
Sample 3	300	297.19	19.88	6.69%
Sample 4	700	706.76	29.77	4.21%

Table 5 Typical test results

300ppm Customer sample stability test
Testing time	Ta（ppm）	Testing time	Ta（ppm）
1	279.71	11	292.07
2	282.04	12	281.43
3	258.35	13	268.94
4	304.35	14	300.44
5	273.6	15	308.38
6	294.01	16	311.98
7	295.1	17	309.29
8	316.05	18	311.01
9	301.58	19	289.85
10	340.26	20	325.42
Standard value (PPM)		300
Average value (PPM)		297.19
Maximum value (PPM)		340.26
Minimum value (PPM)		258.35
Extreme range (PPM)		81.91
Standard deviation (PPM)		19.88
Relative standard deviation (RSD)		6.69%

Table6 300ppm Customer sample stability test

700ppm Customer sample stability test
serial number	Ta（ppm）	serial number	Ta（ppm）
1	707.92	11	683.97
2	690.91	12	661.44
3	696.95	13	703.74
4	708.68	14	712.03
5	702.56	15	670.22
6	764.94	16	707.21
7	713.7	17	682
8	707.92	18	682
9	684.75	19	720.97
10	766.59	20	766.71
Standard value (PPM)		700
Average value (PPM)		706.76
Maximum value (PPM)		766.71
Minimum value (PPM)		661.44
Extreme range (PPM)		105.28
Standard deviation (PPM)		29.77
Relative standard deviation (RSD)		4.21%

Table 7 700ppm Customer sample stability test

6.Conclusion

Through the above tests, our instrument can solve the testing of tantalum content on scandium alloy. Due to the previous technical engineer communicating with the customer, we need to test the sample without tantalum element. Besides, the sample provided previously has no accurate content, and the engineer is making the sample without tantalum standard, so the strength is net strength. In this experiment, it was found that the net strength and stability of tantalum element were not good enough to meet the needs of customers. After adjusting the strength of tantalum element to full strength, the stability is greatly improved. However, tantalum element will be tested when the sample without tantalum element is tested. As its fluorescence intensity is close to that of tantalum element about 200ppm, it cannot be cleared by Cutoff. After asking the sales, we got the reply that the accuracy below 500ppm is not required, but the accuracy and stability above 500ppm should be guaranteed. Therefore, the current application can fully meet customer requirements.