CRM Solutions

How to Digest Nickel 718 Alloy

[fa icon="calendar"] Feb 7, 2018 7:30:00 AM / by Dave Coler

Dave Coler

 

The ColdBlock digestion system is a unique instrument  capable of rapidly dissolving materials for analysis by ICP.  The system uses infrared radiation to speed up  the digestion process and a cooling block  to condense escaping vapor.   In one of our previous  posts "How to digest 316 Stainless Steel for ICP Analysis Using the ColdBlock Digestion System"  we demonstrated the capability of the ColdBlock digestion system for dissolving stainless steel alloys.   In this post we present a method for digesting  Nickel 718 alloy using the ColdBlock system.   Nickel 718 is an austenitic nickel alloy containing significant Cr, Mo and Niobium which can make it challenging to dissolve.    

The  digestion method presented was validated using five replicate digestions of a certified reference material and then analyzed on an ICP-OES.

 

 Digestion Procedure

 5 separate 0.5g aliquots of CRM IARM  56H were prepared using 20ml of aqua regia in a quartz digestion tube.  The 5 digestion vessels were loaded into a 6 position ColdBlock digestion system and digested for 15 minutes at 28% power. After the digestion, 1ml of hydrogen peroxide was added to the solution and allowed to react until  completion. The digested samples were diluted to a total volume of 50ml using deionized water and transferred to a centrifuge tube.  1 ml of HF was then added to each centrifuge tube to stabilize the solution. The samples were then analyzed on a Spectro Arcos ICP-OES in our laboratory.  The results are detailed in the table below.  The reproducibility of the replicate digestions was excellent and the average values generally agree with the certified concentrations.

 

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                            Loading the sample                                                           Sample in Aqua Regia

 20180129_154617 Adding Chips.jpg20180129_155750.jpg

 

                          Digestion Complete                                                                  Sample Diluted

20180129_161140.jpg20180129_162151 Dilute with H2O and add 1 mL H2O2.jpg

 IARM 56H  Alloy 718
Values in %
   Co Standard Deviation     Ti   Standard Deviation
Run #1 0.04130 0.00023  

 Run #1

0.94808 0.000001
Run #2 0.04118 0.00016   Run #2 0.95124 0.000001
Run #3 0.04108 0.00005   Run #3 0.96414 0.000002
Run #4 0.04101 0.00021   Run #4 0.94986 0.000001
Run #5 0.04108 0.00003   Run #5 0.92499 0.000001
Average 0.041128 0.00014   Average 0.94766 0.000001
Certified Value 0.049+/-0.004   Certified Value 0.96+/-0.01
             
   Cr Standard Deviation     Al   Standard Deviation
Run #1 17.81883 0.0000132    Run #1 0.51109251 0.00000038
Run#2 18.00005 0.0000140   Run#2 0.51392712 0.00000040
Run#3  17.71502 0.0000232   Run#3  0.5104183 0.00000036
Run#4  18.02060 0.0000181   Run#4  0.51412924 0.00000053
Run#5 17.48382 0.0000129   Run#5  0.49842327 0.00000006
Average 17.80767 0.0000163   Average 0.50959809 0.00000035
Certified Value 17.86+/-0.06   Certified Value 0.51+/-0.02
             
  Mo Standard Deviation     W Standard Deviation
 Run #1 2.932046 0.000001    Run#1 0.00532587 0.00011
Run#2 2.967717 0.000001     Run#2  0.00553362 0.00004
 Run#3  2.969664 0.000002    Run#3 0.00537084 0.00014
 Run#4  2.97757 0.000002    Run#4  0.00530015 0.00008
 Run#5 2.882191 0.000000    Run#5 0.00530939 0.00007
Average 2.945838 0.000001   Average 0.00536797 0.00009
Certified Value 2.90+/-0.02   Certified Value 0.014+/-0.007
             
  Ni Standard Deviation     V   Standard Deviation
 Run#1 53.09452 0.000003     Run#1 0.02494302 0.0001845
  Run#2  53.74913 0.000089     Run#2  0.02497595 0.0001876
 Run#3 53.72766 0.000046     Run#3 0.02471191 0.0001954
  Run#4  54.81033 0.000021     Run#4  0.02452438 0.0002647
  Run#5 52.02448 0.000054     Run#5 0.02450557 0.0002903
Average 53.48122 0.000042   Average 0.02473217 0.0002245
Certified Value 53.8+/-0.1   Certified Value 0.025+/-0.002
             
  Mn Standard Deviation     Nb Standard Deviation
 Run#1 0.037751 0.0001658   Run#1  5.12186526 0.000004
 Run#2  0.037748 0.0002857    Run#2  5.0887229 0.000004
 Run#3 0.037428 0.0001031    Run#3 4.9762453 0.000008
 Run#4  0.037337 0.0002384    Run#4  5.04930387 0.000005
 Run#5 0.037418 0.0001837     Run#5 4.93893093 0.000003
Average 0.037536 0.0001953   Average 5.03501365 0.000005
Certified Value 0.040+/-0.003   Certified Value 5.20+/-0.03
             
  Ta Standard Deviation     B Standard Deviation
 Run#1 0.004808 0.0002147   Run#1 0.00418752 0.00005
 Run#2  0.004762 0.0001046   Run#2   0.0039845 0.00004
 Run#3 0.004703 0.0001393   Run#3  0.00390868 0.00002
 Run#4  0.004753 0.0001821    Run#4  0.00391604 0.00002
 Run#5 0.00484 0.000139   Run#5  0.00394484 0.00002
             
Average 0.004773 0.0001559   Average 0.00398831 0.00003
Certified Value 0.006+/-0.002   Certified Value 0.0045+/-0.0003
             
  Mg Standard Deviation     Fe Standard Deviation
 Run#1 0.001043 0.000014   Run#1  18.1270151 0.00001
 Run#2  0.001034 0.000028   Run#2  18.3409909 0.00002
Run#3 0.001041 0.000013   Run#3  18.0247494 0.00003
Run#4  0.001095 0.000008   Run#4   18.3954097 0.00002
Run#5 0.001063 0.000018   Run#5 17.8302087 0.00002
Average 0.001055 0.000016   Average 18.1436747 0.00002
Certified Value 0.0010+/-0.0001   Certified Value 18.6+/-0.1
             
Values in PPM
  Cu   Standard Deviation     Si Standard Deviation
Run#1 142.988 0.0002072   Run#1  576.307 0.000271
 Run#2  130.488 0.0006184   Run#2   570.786 0.000097
 Run#3 112.514 0.0006258   Run#3 551.729 0.000268
 Run#4  109.833 0.0001455   Run#4  549.176 0.000409
 Run#5 113.052 0.0004433   Run#5  552.685 0.000129
Average 121.775 0.0004080   Average 560.1366 0.000235
Certified Value 120+/-20   Certified Value 540+/-30

 

 

 


 

Topics: 718 alloy, coldBlock, icp sample preparation

Dave Coler

Written by Dave Coler

General Manager at LGC ARMI