Comparative Performance of Nickel Release Test Procedures: EN 1811:1998 and PD CR 12471:2002

Transcription

1 Comparative Performance of Nickel Release Test Procedures: :1998 and PD CR 12471:2002 Dippal Manchanda MSc CSci CChem FRSC Technical Director & Chief Assayer

2 :1998 vs PD CR 12472:2002 Background of the Study ( ) The Birmingham Assay Office (BAO) was invited by NiPERA to compile a report concerning the comparative performance of the two tests - PD CR 12471:2002 Nickel Screening Test and :1998 based on the test results. A set of eleven homogeneous materials were chosen for this work. Four leading international laboratories participated in this project. Results confirmed that PD CR 12471:2002 itself is not sufficiently accurate to be used as an alternative to : If testing is carried out by any of the three Nickel Screening testing approaches (Pre Test, Lab Test, Field Test), approximately 17% of non-compliant material could reach the market place. This Presentation is the summary of the study submitted by the Birmingham Assay Office to NiPERA in 2006.

3 NiPERA Project: Test Materials Material 1 - Metallic Nickel Material 2 - Cupro/Nickel Material 3 - German Silver Material 4 - Monel Metal Material 5 - Carbon Steel Material Stainless steel Material Stainless steel Material Stainless steel Material 9 - Nitinol Material Stainless steel Material carat white gold Prior to testing these materials were analysed for their complete composition by ICP-OES and other appropriate techniques for both major and minor metallic elements, including sulphur and carbon.

4 An Example of Test Coupons

5 Sample Preparation Test coupons (20 x 20 x ~2 mm) were cut from the supplied flat sheet / bar and identified by a unique number lightly stamped on the rear surface of each coupon. A hole was drilled into each coupon to enable suspension during testing. The surfaces of the coupons were then carefully prepared and a high finish, equivalent to nearly 6 microns was achieved using a diamond paste, plus polishing pads. All samples were then cleaned with RBS detergent to remove any organic residue on the surface. Each sample was visually inspected for appearance and surface defects, which if observed were corrected by an appropriate means in an attempt to minimize any surface variation.

6 Distribution of Test Material Four sets of samples were prepared for distribution to four participant laboratories (Lab 1, Lab 2, Lab 3 and Lab 4) According to the agreed testing protocol, three coupons of each material were supplied for testing by :1998; these coupons were to be tested on three separate days One coupon of each material was supplied for testing according to each of the three PD CR 12471:2002 tests the Pre-test, Laboratory test and Field test. In total six coupons of each material were supplied, resulting in a total of 66 (6 x 11) coupons being sent to each laboratory

7 Test Methods PD CR Nickel Screening test. This procedure details 3 different test methods: Pre-test Laboratory test Field test : 1998 As specified in the standard (Now withdrawn)

8 Pass/Fail Criteria The following criteria were observed while evaluating the tests results: Nickel Release Test (:1998): Passing : Adjusted nickel release 0.5 µg/cm 2 / week Failing : Adjusted nickel release > 0.5 µg/cm 2 / week Nickel Screening test (PD CR 12471:2002): Negative Test - No pink colour - indicating no release of nickel Positive Test - Pink colour - indicating release of nickel Uncertain - Not Sure about the results.

9 Results It was expected that all four laboratories would produce similar nickel release values for the 11 materials tested, following the procedure specified in and PD CR However on the contrary, when examining the results reported it was observed that they did not show a good level of agreement for most of the materials.

10 Material No.1 Metallic Nickel Composition Cu (%) Mn (%) Ni (%) Fe (%) Co (%) Mg (%) C (%) Total (%) Results* Mean Mean 0.13 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB ~ Mean 0.56 LAB 3 LAB , +, , +, ~, ~, Mean 0.57 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

11 Material No.2 Cupro-Nickel Composition Cu (%) Mn (%) Ni (%) Fe (%) Zn (%) Mg(%) C (%) S (%) Total (%) Results* Mean Mean 9.19 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Field Pre-Test Lab Test Test LAB 1 LAB Mean LAB 3 LAB 4 +, +, + +, +, + +, +, Mean *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

12 Material No.3 German Silver Composition Cu (%) Mn (%) Ni (%) Fe (%) Zn (%) C (%) Total (%) Results* Mean Mean 2.91 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB Mean 0.77 LAB 3 LAB , +, , +, , +, Mean 3.53 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

13 Material No.4 Monel Metal Composition Cu (%) Mn (%) Ni (%) Fe (%) Mg (%) Cr (%) Mo (%) C (%) S (%) Total (%) Results* Mean Mean 3.85 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB Mean 1.44 LAB 3 LAB , +, , +, , +, Mean 4.67 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

14 Material No. 5 Carbon Steel Composition Cu (%) Mn (%) Ni (%) Fe (%) Cr (%) C (%) S (%) Total (%) Results* Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB Mean Mean ~ LAB 3 LAB , +, ~, ~, ~ ~, ~, ~ Mean 0.01 Mean 0.00 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

15 Material No Stainless Steel Composition Cu (%) Mn (%) Ni (%) Fe (%) Co (%) Cr (%) Mo (%) V, C, S (%) Total (%) , 0.08, Results* Mean Mean 0.01 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB Mean 0.01 LAB 3 LAB , -, , -, , -, Mean 0.00 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

16 Material No Stainless Steel Composition Cu (%) Mn (%) Ni (%) Fe (%) Co (%) Cr (%) Mo (%) V, C, S (%) Total (%) , 0.08, Results* Mean Mean 0.01 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB Mean 0.01 LAB 3 LAB , -, , -, , -, Mean 0.00 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

17 Material No Stainless Steel Composition Cu (%) Mn (%) Ni (%) Fe (%) Co (%) Cr (%) Mo (%) V, C, S (%) Total (%) , 0.12, Results* Mean Mean 0.01 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB Mean 0.01 LAB 3 LAB , +, , -, , -, Mean 0.00 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

18 Material No. 9 Nitinol Composition Mn (%) Ni (%) Ti (%) C (%) Total (%) Results* Mean Mean 1.63 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB ~ Mean 0.42 LAB 3 LAB , -, , -, , -, ~ 3. - Mean 1.63 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

19 Material No Stainless Steel Composition Cu (%) Mn (%) Ni (%) Fe (%) Cr (%) Mo (%) C (%) S (%) Total (%) Results* Mean Mean 0.68 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB ~ Mean 0.20 LAB 3 LAB , ~, , ~, ~ ~ 3. - ~, -, Mean 0.30 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

20 Material No carat White Gold Composition Au (%) Cu (%) Ni (%) Zn (%) Ag (%) Fe (%) Pb (%) Mn (%) Total (%) Results* Mean Mean 0.01 Nickel Screening Test Results# Nickel Screening Test Results# Pre-Test Lab Test Field Test Results* Pre-Test Lab Test Field Test LAB 1 LAB Mean 0.02 LAB 3 LAB , +, , +, ~ +, +, Mean 0.00 *Adjusted nickel release (µg/cm 2 / week), Test Results# + =(Positive - Indicating Ni release), - = (Negative - Indicating no Ni release ), ~ = (Uncertain Not sure),

21 18 carat white gold material at 500x magnification The microstructure consists of a predominant primary phase, composed from Au, Cu, Zn and Nickel. The alloy is quite homogeneous which explains the reason for low nickel release rate when tested by. There is however a secondary phase that is Ni rich which is responsible for the positive results obtained for this material when tested by the Nickel Screening test.

22 Analysis of Results The analysis of the results was a tough job particularly when a set pattern in the results was not visible; a particular material passed the nickelrelease test on one occasion, but failed when tested again. Also, a material sometimes passed by one laboratory, but was failed by others. To make the analysis of results understandable and meaningful, the average EN 1811 Nickel Release value reported by individual laboratories for each test material was compared with the results of Nickel Screening tests - PD CR reported by all four laboratories. Any uncertain results were excluded when analysing these results. Total Results: (Pre Test / Field Test - 12 results X 11 alloys X 4 EN1811= 528 results) (Lab Test - 18 results X 11 alloys X 4 EN1811= 792 results)

23 Summary Comparative Performance of Nickel-Release Test Procedures Description Pre-Test Lab Test Field Test Total Total negative Screening test and passing (i.e. Pass-Pass) 257 (82%) 284 (84%) 171 (80%) 712 (83%) Total negative Screening test and failing (i.e. Pass-Fail) (18%) (16%) (16%) (17%) - False Negative. Total (Negative Screening test ) Total positive Screening test and failing (i.e. Fail-Fail) 154 (74%) 251 (66%) 182 (57%) 587 (65%) Total positive Screening test and passing (i.e. Fail-Pass) (26%) (34%) (43%) (35%) - False Positives. Total (Positive Screening test ) No. Of Uncertain Results Total Results

24 Conclusion If inspection is carried out according to PD CR 12471:2002: 1. 17% of non-compliant articles could reach the market place False Negative. 2. We may fail 35% of articles which will actually be compliant when tested by EN1811:1998. False Positive. This conclusion is limited to the 11 materials tested. The overall situation may be better or worse, if a larger number of materials were to be tested. Current compliance limit is 18 times lower than EN1811:1998 version. Can a DMG based test accurately detect such a low level of nickel????

25 Any Questions Dippal Manchanda MSc CSci CChem FRSC Technical Director & Chief Assayer ANCHORCERT ANALYTICAL 1 Moreton Street Birmingham, B1 3AX, ENGLAND Dir: +44 (0) Mob: +44 (0) dippal.manchanda@theassayoffice.co.uk