Modeling of Component Lifetime Based on Accelerated Acid Gas Permeation Measurements

Modeling of component lifetime based on accelerated acid gas permeation measurements

Gary Van Schooneveld, Don Grant, Debra Carrieri, Dennis Chilcote and Mark Litchy

February 11, 2009

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 1 Introduction

• Metallic parts in chemical handling systems are subject to corrosion by acid gases like hydrogen chloride (HCl) and hydrogen fluoride (HF). – Examples include springs in valves and magnets in mag drive and maglev pumps • Polymers, like perfluoroalcoxy (PFA), are often used to isolate these parts from acid gas containing liquids to prevent corrosion. • Acid gases in these liquids can permeate through polymers and corrode the parts. • One objective of this study was to determine the rates at which HCl and HF permeate through various polymers that could be used to encapsulate Levitronix pump impellers as a function of coating thickness, acid concentration and temperature. • The second objective was to determine pump impeller lifetime under controlled conditions. • The third objective was to combine the results of the first 2 objectives to develop a model to predict the lifetime of pump impellers coated with different polymers under different operating conditions.

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 2 Outline • Diffusion theory • Permeation rate measurement experimental procedures • The effect of operating conditions on permeation rate thru PFA – Concentration – Temperature – PFA thickness • Permeation rates of HCl and HF thru various polymers • Life test status • Predicted relative lifetimes under different operating conditions • Summary

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 3 Steady-state permeation

Ρ AP M = V T

Where M = Mass flow rate P = Permeability coefficient PV = Gas vapor pressure A = surface area available for diffusion T = material thickness

Note: The mass flow rate is proportional to the gas vapor pressure; not the acid concentration.

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 4 Partial pressure of HF over hydrofluoric acid solutions

101

100 )

g 10-1

m 10-2

(

e -3

r 10

u s

s 10-4 e

r 10-5

o p

a 10-6 V 80 ) -7 70 % 10 t 60 h ig 10-8 50 we ( 80 40 n 70 tio 30 a 60 tr n 50 20 e Te 40 c Source: Brosheer at all, Ind and Eng Chem mpe 30 10 n 39(3):423-427, 1947 and Hydrofluoric ratu Co re ( 20 0 Acid Properites, Honeywell (2002). °C) 10

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 5 Comparison between vapor pressures of HF and HCl over hydrofluoric and hydrochloric acids

HF HCl

101 101 100

100

) )

g -1

10 -1 H

m 10

a m

-2 (

m -2

( 10

e -3 s

r 10 s -3

u 10

e s r

s -4

10 p e

-4 r

r 10

10-5 p o

a 10-5

a 10-6 C V 80 10-6

) H -7 70 80 10 % ) 60 t 10-7 70 % gh t -8 60 h 10 50 ei ig (w 10-8 50 e 80 40 w on ( 70 30 i 80 40 n 60 rat 70 tio t 30 a 50 20 60 tr en n Te 40 c 50 20 e mp 30 10 on T 40 c era C em 10 n ture 20 0 pe 30 o (°C 10 ratu 20 C ) re ( 0 °C) 10

Source: Brosheer at all, Ind and Eng Chem 39(3):423-427, 1947 and Hydrofluoric Source: JH Perry, Chemical Acid Properites, Honeywell (2002). Engineers’ Handbook, 4th Edition, McGraw Hill (1963) p 3-61

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 6 Comparison of HCl and HF vapor pressures

Vapor pressure of HCl over selected hydrochloric acid solutions

HCl concentration Temperature Vapor pressure (% by weight) (°C) (atm) 5 20 5.5 x 10-7 6.3 75 2.1 x 10-4 37 20 0.17 37 40 0.55 32 75 0.66 37 60 1.51

Vapor pressure of HF over selected hydrofluoric acid solutions

HF concentration Temperature Vapor pressure (% by weight) (°C) (atm) 0.5 20 1.2 x 10-5 5.0 20 7.5 x 10-5 49 20 0.018 49 60 0.15

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 7 Experimental approach – permeation measurements

• Determine the effects of vapor pressure, temperature and coating thickness on permeation rates of HF and HCl through PFA. • Measure the permeation rate of HCl through various polymers as a function of temperature. – Polyethylene (PE) – Polypropylene (PP) – Polyvinylidene dofluoride (PVDF) – Ethylene-chlorotrifluoroethylene (ECTFE) – Perfluoroalcoxy (PFA) - 3 types – Polytetrafluoroethylene (PTFE) • Measure the permeation rate of HF through various polymers at room temperature. – Polypropylene (PP) – Polyvinylidene dofluoride (PVDF) – Ethylene-chlorotrifluoroethylene (ECTFE) – Perfluoroalcoxy (PFA) – Polytetrafluoroethylene (PTFE)

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 8 Test System Schematic

Flow Meter/Controller

CDA

Test Specimen

HCl Solution Scrubber Temperature Controlled Chamber

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 9 Test conditions

• Effect of concentration, temperature, and thickness on permeation rate: – HCl • Concentrations: 14-36% by weight • Temperatures: 30-75°C • 3 thicknesses (1.0, 1.5 and 2.0 mm) – HF • Concentrations: 5-49% by weight • Temperatures: 33-60°C • Comparison of polymer permeation rates – HCl • 35% by weight • Temperatures: 30-55°C – HF • 49% by weight • 33°C • All tests run in triplicate

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 10 1200 33°C 1000 Sample #1 Sample #2 Sample #3 Blank #1 800 Blank #2 Example of permeation 600 data – 49% HF at 3 400 temperatures Total mass permeated(µmoles) 200

0 0 5 10 15 20 25 Time (days)

1200 1200 46°C 60°C Sample #1 Sample #1 1000 1000 Sample #2 Sample #2 Sample #3 Sample #3 Blank #1 Blank #1 800 Blank #2 800 Blank #2

600 600

400 400 Total mass permeated (µmoles) mass Total permeated Total massTotal permeated (µmoles) 200 200

0 0 0 5 10 15 20 25 0 5 10 15 20 25 30 Time (days) Time (days)

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 11 The effect of vapor pressure, temperature, and thickness on the permeation rates of HCl and HF through PFA

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 12 The effect of temperature and hydrochloric acid concentration on HCl permeation rate through 1.5mm thick samples 100

14% HCl 20% HCl 27% HCl

- day) 10 36% HCl 2

0.1 Permeation rate (µMoles/cm Permeation

0.01 30 40 50 60 70 80 Temperature (°C)

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 13 Permeability coefficient

Ρ AP M = V T

Where M = Mass flow rate P = Permeability coefficient PV = Gas vapor pressure A = surface area available for diffusion T = material thickness

Permeability coefficient units

Gas volume – thickness ------Area in contact with gas– Time - Vapor pressure

cm3 (g) – mm ------m2 – day - atm

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 14 The effect of temperature on the permeability coefficient of HCl through PFA

10000 - day - atm) - day 2

1000 (g) - mm / m (g) 3

100

14% HCl 20% HCl 27% HCl 1.5mm thick samples 36% HCl Permeability coefficient (cm 10 25 30 35 40 45 50 55 60 65 70 75 80

Temperature (°C)

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 15 The effect of thickness on the permeability coefficient of HCl through PFA

10000 - day - atm) - day 2

1000 (g) - mm / (g) m 3

100 14% HCl 20% HCl 27% HCl 36% HCl 1.0 mm thick 2.0 mm thick Permeability coefficientPermeability (cm 10 25 30 35 40 45 50 55 60 65 70 75 80 Temperature (°C)

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 16 The effect of temperature on the permeability coefficient of HF through PFA

10000 -day-atm) 2

1000

(g)-mm/M 49% HF 3 27% HF 5% HF

100 Permeation Coefficient (cm 10 25 30 35 40 45 50 55 60 65 70 75 80 Temperature (° C)

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 17 Permeation of HF and HCl through PFA

• Permeation rate – Is proportional to the acid gas vapor pressure – Increases with temperature – Is inversely proportional to the coating thickness • The HCl permeation coefficient increases more rapidly with temperature than the HF permeation coefficient. – HCl permeability increased 2.5X between 30 and 60°C – HF permeability increased 2.1X between 30 and 60°C • The HF permeation coefficient is larger than the HCl permeation coefficient at typical use temperatures: – 15X at 30°C – 12X at 60°C

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 18 Polymer permeability comparison

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 19 Permeation coefficient of HCl through different polymers

10000 PE PP PVDF ECTFE Daikin AP-211SH PFA

-day-atm) Dupont 440HP PFA 2 Dupont 940HP PFA PTFE 1000 (g)-mm/M 3

100 Permeation coefficient (cm 10 25 30 35 40 45 50 55 60 65 70 75 80 Temperature (C)

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 20 Permeation coefficient of HCl through different polymers

800

33oC -day-atm) 2 600 (g)-mm/M 3

400

200

Permeation Coefficient (cm 0 PE PP PVDF ECTFE PFA PTFE Prop Coating Polymer

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 21 Permeation coefficient of HF through different polymers

10000

33oC -day-atm) 2 8000 (g)-mm/M 3

6000

4000

Permeation Coefficient (cm 2000 PP PVDF ECTFE PFA PTFE Prop Coating Polymer

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 22 Comparison between HCl and HF permeation coefficients

Permeation coefficient, cm3(g)-mm/M2-day-atm Polymer HCl HF PE 430 - PP 600 4200 PVDF 75 8800 ECTFE 45 3600 PFA 300 2600 PTFE 250 2700 Proprietary Coating 8 2600

@ 33oC

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 23 Comparison between HCl and HF permeation rates with “as-received” acid

Relative permeability Vapor pressure, atm Relative permeation rate Polymer HCl HF 37% HCl 49% HF 37% HCl 49% HF PE 9.6 - 0.44 0.043 4.3 - PP 13.3 93 0.44 0.043 5.9 4.0 PVDF 1.7 196 0.44 0.043 0.76 8.4 ECTFE 1.0 80 0.44 0.043 0.44 3.4 PFA 6.7 58 0.44 0.043 3.0 2.5 PTFE 5.6 60 0.44 0.043 2.5 2.6 Coated PFA 1.4 58 0.44 0.043 0.63 2.5

@ 33oC

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 24 Component lifetime predictions

Assumption: Component lifetime is inversely proportional to the rate at which the acid gas reaches the component.

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 25 Predicted PFA coated component life based on HCl permeation rate (assumes that failure rate is proportional to permeation rate)

107

106

t 5

a 10

C H

104

2 3 3

o 10

v i

t 2

a 10

e 101

e f i 0 L 10 40 ) 35 % -1 ht 10 30 eig 70 25 (w on 60 20 ati 50 15 ntr ce 40 10 on Te 30 l c mp 5 C (°C) 20 H

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 26 Predicted relative lifetimes of PFA coated components under expected use conditions

Concentration Acid Temperature (°C) Relative lifetime (weight %) 6.3 75 3,100 37 20 22 HCl 37 40 2.7 32 75 1.0 0.5 20 8,400 HF 5 20 1,350 49 20 5.5

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 27 Impeller life tests

• Three studies on-going • BPS3 pump circulating 35-37% HCl at room temperature – PVDF housing – ECTFE impeller magnet encapsulation • BPS1, BPS3 and BPS4 pumps are circulating 30-32% HCl at 75°C. – Pump body • BPS3 – PFA • BPS1 and BPS4 - PTFE – PFA impeller magnet encapsulation • Static soak of PFA impellers with two encapsulation thicknesses (1.4 mm and 0.7 mm) in 30-32% HCl at 70°C. • No contamination related failures have been observed in any of the tests.

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 28 Levitronix design approach for contamination prevention

• Pumps are designed sense and respond to changes to impeller size. • The response provides an early indication of impeller swelling due to magnet corrosion. • These accelerated life tests are designed determine: – when the impeller size changes enough for the pump to sense and respond to impeller swelling (useful service life) and – if or when metal ions are released from the impeller (safe life) • Goal is to have a safe life well beyond the useful service life of the impeller.

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 29 Predicted lifetimes based on pumps and impellers currently under test

Average Service Safe Life Service Safe Life Average Pump Run Time HCl Life @ @ Life @ @ Temp Model (Days) Assay 37%/20oC 37%/20oC 6.3%/75oC 6.3%/75oC (oC) (wt%) (Years) (Years) (Years) (Years)

BPS 3 2150 RT 35-37 > 5.9 > 5.9 > 830 > 830

BPS 1 546 70.0 28.7 10.5 > 12.0 1,500 > 1,700

BPS 3 590 74.4 29.9 15.5 > 19.9 2,200 > 2,800

BPS 4 590 74.3 30.2 > 20.7 > 20.7 > 2,900 > 2,900

BPS 3 115 69.9 30.6 > 3.2 > 3.2 > 450 > 450 Impellers

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 30 Summary • The permeation rate of HCl and HF through PFA was shown to: – Be proportional to the HCl or HF vapor pressure – Be inversely proportional to the coating thickness – Increase with temperature • The permeation rates of HCl and HF through different polymers indicated that comparisons between HCl permeation rates through different polymers are not a good indicator for HF permeation rates through the same polymers (and vice versa). • A model was developed to predict component failure rate resulting from acid gas (HCl or HF) permeation. • The model, combined with on-going life test data, predicts pump lifetimes with PFA-coated impellers > 10 years under challenging use conditions. • All observed failures have been pump efficiency related. No failures resulting in chemical contamination have be observed in any of the tests.

G Van Schooneveld et al (2009). Presented at the Ultra Pure Fluid and CT Associates, Inc. Wafer Cleaning Conference 2009, sponsored by Levitronix. Slide 31