1. Atmosphere Recovery, Inc.
High Performance, Low Emission Carburizing Furnace Atmosphere Generation & Control Using Rapid Laser-Based Gas Analysis October 11, 2000
Ronald R. Rich
Atmosphere Recovery, Inc.
and
Ralph W. Larson
Dana Corporation

2. Topics Presented Carburizing Atmosphere Technology & Issues
Atmosphere Gas Monitoring Needs & Methods
ARI Laser Gas Analyzer (LGA)/Controller System
Improved Process Development History
New Approaches to Gas Carburizing with LGA
Metallurgical Findings & Technology Status

3. Carburizing Use & Purpose
Typical Parts (Gears)
Typical Furnace (Batch)
Improves Steel Wear Resistance on Part Surfaces (Adds Carbon)
Maintains Steel “Toughness” at Part Depth (Lower Carbon)
Parts to Heated to High Temperatures in a Gas “Atmosphere”
Atmosphere Provides Reactive Chemistry Containing Carbon in Gas Form in a Reducing Environment

4. Traditional Carburizing Atmosphere
Composition: CO~20%, N2~39%, H2~39%, 1% CH4, Balance: CO2, H2O, O2
Air
Exhaust Stack
Endogas
At Metal Surface:
2H2+2CO+3Fe  Fe3C+2H2O+CO2
3Fe + CH  Fe3C + 2H2
Natural Gas

5. Typical Carburizing Operation

6. Major Concerns Related to Atmosphere Carburizing
Process Control Problems with Existing Technologies
Variable Production Part Parameters (Case Depth, %Carbon)
Many Atmosphere Constituents Inferred
Inefficient Control Algorithms to Employed to Reduce Sooting
Limited Warning of Equipment Maintenance
Process Improvement Potential (Over 60 Years Old)
Improved Part Quality & Performance
Reduced Atmosphere Consumption
Furnace Cycle Time Reductions
Higher Performing Surface Treatment Options
High Levels of Carbon Monoxide Air Emissions
Inefficient Use of Atmosphere Gas and Energy

7. Most Industrial Furnace Atmosphere Gases Similar
Carburizing, Carbonitriding, & Nitriding
N2, CO, H2, CO2, H2O, CH4, O2, NH3, CH3OH
Atmosphere Tempering and Annealing
N2, H2, CO, CO2, H2O, CH4, O2, NH3, Ar
Copper and Aluminum Brazing
Powdered Metal Sintering
N2, CO, H2, CO2, H2O, CxHy, O2

8. Typical Atmosphere Control Measures Only One Gas Species
Types
Zirconia Oxygen Probe – Measures Oxygen
Dew Point Meters – Measures Water Vapor
Electrochemical Cells – Low Range Single Gases
Benefits
Lower Capital Cost
Limited Calibration Requirements
Disadvantages
All Other Gas Constituents Not Measured or Controlled
Many Assumptions About Other Gas Constituents Needed
Requires High Atmosphere Flows for Adequate Control
Inaccurate Correction for Most Atmosphere Variances
Limited Process Control Variation & Improvement Options

9. Carburizing Atmosphere Monitoring Improved With Infrared Analyzers
Usually Measures Only Three More Gases
Carbon Monoxide
Carbon Dioxide
Methane
Does Not Measure Other Significant Gases
Oxygen (Additional Sensor Required)
Water Vapor (Theoretically Could)
Hydrogen
Nitrogen and Inert Gases
Non-Linear Response
Accurate Only Within Limited Concentration Range
High/Low Constituent Concentration Interference
Reference Cell Requires Frequent Calibration

10. Benefits of Complete Atmosphere Gas Analysis
Improved Carbon & Nitriding Potential Control
Improved Oxidation/Reduction Potential Control
Reduction in Atmosphere Consumption
Allows Use of “Non-Standard” Atmosphere Gases
Control of “Cleaner” Furnace Atmospheres
Hydrogen/Nitrogen/Inert Combinations
Carbon Dioxide/Hydrocarbon Mixtures
Novel Mixtures for Improved Performance
Sooting Reduced or Eliminated
Early Warning of Some Furnace Maintenance Issues
Potential for Reduced Furnace Cycle Times

11. Additional Benefits if Complete Atmosphere Analysis is Rapid (15 Seconds or Less)
“Real Time” Process Monitoring, Control and R&D
Correlation with Existing Furnace Sensors
“Non-Equilibrium” Atmosphere Operation
Accurate Carburizing Rate Assessment
Greater Potential for Reduced Furnace Cycle Times
Drastic Reduction in Atmosphere Consumption
Efficient Use of “Non-Standard” Atmosphere Gases
Early Warning of Many Furnace Maintenance Issues
Improved Furnace Performance and Safety Monitoring

12. Conventional Complete Gas Analysis Technologies
Gas Chromatography (GC)
Moderate Price ($15,000 - $60,000)
Slow (2 Minutes+)
Frequent Calibration and Service
Carrier Gas Needed
Mass Spectroscopy (MS)
Higher Price ($50,000 - $120,000)
Fast if Vacuum Already Present (Can be Slow if Not)
Expensive to Maintain
Equal Mass Gases Require Additional Analysis (GC)

13. Raman Gas Analysis Principals
Unique Frequency “Shift” for Each Type of Chemical Bond
Measures Gases of All Types (Except Single Atoms)
Rapid “Real Time” Response Rates Possible
Signal Directly Proportional to Number of Gas Atoms
0-100% Gas Concentrations Measured with One Detector
Resolution and Accuracy Depends On:
Laser Power and Optics Variation (Including Cleanliness)
Gas Concentration and Pressure
Molecular Bond Type
Background and Scattered Radiation
Optical and Electronic Detector Circuitry

14. Some Atmosphere Raman Shift Spectra
Source:
NASA

15. Laser Raman Analysis Technologies
External Cavity Raman Lasers (Under Development)
Remote Fiber Optic Sensor Heads
Higher Price Because of High Laser Power ($75,000 - $300,000)
Fast Only if Laser Power High
Expensive to Operate (Power, Cooling, Probe Tip?)
Laser Beam Dangerous
Less Accurate
Internal Cavity Raman Laser (ARI’s “LGA” Design)
Gas Sample Flows Through Instrument
Moderate Price ($25,000 - $60,000)
Fast if Detectors Selective
Low Cost Operation
Safe Low Power Laser Beam

16. Multiple Port ARI LGA System
Furnace Gas 1 In
Filter
Assembly
Valve
Filter
Furnace Gas 3 In
Furnace Gas 2 In
Filter
Filter
Generator Gas In
Individual Gas Detectors
Individual Gas Detectors
Gas Sample Tube
Laser Beam
Plasma Cell
Mirror
Prism & Mirror
Polarizer
Sample Pump & Pressure Control
Gas Outlet

17. ARI LGA Detector Features
Gas Analysis Capabilities
8 Gas Species Detected Simultaneously
Fast Detector Response (50 milliseconds)
50 Parts per Million to 100% Concentration Range
More Accurate than NIST Calibration Gas Mixtures
No Zero and Span Gas Requirement (Optional)
Design Allows Customized Selection of Gas Species
Lifetime and Servicing
Two to Five Year Component Lifetimes
Ten Minute Detector Exchange
Individual Components Can Be Serviced and Cleaned

18. Additional LGA System Features
Integrated Sample Flow Control & Monitoring
Specialized Long Life Sample Filters (One Year +)
Internal Sample Pump and Calibration Valves
Low Volume Sample Gas Flows (200 ml/minute)
Electronic Flow and Pressure Monitoring
Optics and Enclosure Inerting (Standard for Atmosphere Analysis)
Multiple Sample Ports (16 + Optional)
Sample Line Purge and Back-flush (Optional)
High Dew Point Atmosphere Operation (Optional)
Integrated Electronics & Software
“Open Hardware” Pentium/Pentium III PC
“Open Software” Windows NT 4.0/Win2000 Based
Many Local and Remote Displays and Data Storage Options
Available Analog and Digital I/O Options
Multiple Configurable Process and PLC Interface Options

19. Interior View of Subsystems
Display, Keyboard,
Serial & Network Ports
Laser & Gas Sensor
Assembly
Optional I/O
Card Slots
Gas Flow Control
Assembly
Pentium PC Based
Monitor/Controller
Gas Sample Pump
Win NT or DOS OS
& 4.3 GB Hard Disk
Multi-Port
Control Options

20. Exterior View NEMA 4/12 Unit
(131oF
Maximum)
Model 4EN
Furnace Atmosphere Analyzer
Cooling
Unit
Electrical &
Communication
Sample, Calibration &
Inerting Gas Inputs

21. Interior View NEMA 12 Unit
LGA Unit
Sub-Assembly
Integrated
Multi-port
Valves
Integrated
Sample Filters
Power & Network
Connections
Calibration &
Purge Gas
Regulators

22. Sample Software Control Screens
Main Control Screen
Atmosphere Analysis Values

23. LGA Carburizing Applications
External Atmosphere Generator Monitoring & Control
Complete Furnace Atmosphere Control Including:
Communications with PLC-Based Furnace Controller
Real-Time Carbon Potential Correction of Oxygen Sensor
Reduced Atmosphere Gas Usage & In-Situ Generation
Stand-Alone PC Based Control System Integrating:
Complete Furnace Atmosphere Control
Improved Safety Monitoring
Burner & Over Temperature Modules
Oxygen Probes & Quench Tank Monitoring
Part Load and Tray Tracking
Interface with Plant SCADA and SPC Systems

24. Use for Rapid Generator Monitoring
Expanded View Showing Rapid Variations

25. New Approaches to Carburizing Demonstrated at Dana Corp.
Spicer Off-Highway Components
Plymouth, MN

26. Plant Products and Processes
Primarily Large Off-Road Axles and Gearsets
Some Interdivisional Component Carburizing
Atmosphere Heat Treat Processes
Five “Carburizing” Furnaces
Three “Endothermic” Generators

27. Improvements Initiated Because of New Air Emission Concerns
Previously Recognized Air Emissions
Smoke from Quenching
Burner Combustion Gases
Unrecognized Air Emissions Issues
Carbon Monoxide (CO) from Atmosphere Use
Comes from Atmosphere Generation, Leakage
and Flaring - 10,000 to 200,000 ppm
Original “Potential to Emit” Estimate Tons Per Year (TPY)

28. Rapid Gas Analysis Process Development
Environmental & Air Quality Monitoring
Furnace Gas and Emission Testing
Options for Industrial Furnace Process Modification Identified
Atmosphere Recovery, Inc. Founded
Carburizing Heat Treat Furnace Atmosphere Recovery Research
Dana & USDOE Sponsored Research Program
Intent to Produce Systems
Constructed and Tested Prototype Systems
Numerous Papers and Presentations
Plant and Process Energy and Environmental Awards
– Laser Gas Analyzer Product Demonstrations
Endothermic and Exothermic Applications
Tests with “Non-Standard” Atmospheres

29. Batch Furnace Modifications
Side Pipe Waste Gas Exit with Cap
Backup Safety Pressure Control Box and Dials
Electronic Endothermic Gas Control
Communication with Existing Controls
Finding - Minimal Modifications Needed

30. 2,000 lbs. Driveshaft “Crosses”
Typical Test Load
2,000 lbs. Driveshaft “Crosses”
Side View
Top View

31. Initial Demonstration - Atmosphere Recovery Process
IR-GC
Later LGA
Part of System

32. IR-GC (Later Replaced by LGA)
Prototype System
IR-GC (Later Replaced by LGA)
Prototype Development, Assembly and Testing
First Full Scale Operation - Aug. 6, 1997
Finding - Process Worked and Increased Furnace Productivity

33. Inter-Cavity Raman & GC Comparison on ARI Trial

34. System Location in Plant
“Explosion Resistant” Test Area

35. Later Demonstrations - Integral Atmosphere Generation
LGA is
Integral
Part of System

36. Example Results for Rapid Carburizing

37. Parts Testing – Typical Load
Two Test Pins
One by Plant
One by Heavy Axle Division (HAD)
3 or 6 “Standard Heat Code” 8620 Planet Gears Per Load
Tested by Plant
Standard Load Locations
Three As Tempered
Sometimes Three as Quenched
Three 8620/25/30 Test Pinions (Production Parts)
All As Tempered
One Tested by Plant
Two Tested by HAD
Two Carbon Profiles (Bar by HAD, Rod by Plant)

38. Case Depth and Profile of Parts
RC50 Value Case Depth Always Obtained Faster
Improvement Percentages Depends Primarily on Desired Final Case Depth (Shallower is Faster)
Less Case Depth Variation in Load
Hardness and Carbon Profile Consistent
Profiles Consistent with Higher Surface Carbon Potentials
Surface Hardness Also Acceptable
Surface Cleanliness not Significant (8620/8625/8630)

39. Retained Austenite/Carbides in Parts
Baseline
ARI Accelerated
“ARI Process Better (Lower Levels)”
Levels Can Be Adjusted to Suit Desired Result
Controllable Even with Wide Atmosphere Fluctuations

40. Grain Boundary Oxidation in Parts
Baseline
ARI Accelerated
“ARI Process Better (Lower Levels)”
Levels Can Be Adjusted to Suit Desired Result
Controllable Even with Wide Atmosphere Fluctuations

41. Metallurgical Findings Summary
Batch Cycle Times Faster (Load to Unload)
Same Process Temperature (Typically 1750 Deg. F.)
Case Depth of .040” – 35% to 50% Faster
Case Depth of – 20-30% Faster
Less Case Depth Variation Though the Load
Controllable Carbon Content/Hardness Profile
Controllable Retained Austenite Levels
Controllable Iron Carbide Levels
Wide Variation in Atmosphere Constituents Tolerated
Advanced Soot Control Algorithms Do Not Affect Parts
All Parts Released for Production

42. ARI Technology Status
Laser Gas Analyzer/Controller Systems Sales & Service
Carburizing (Current Sales)
Annealing (Current Sales)
Nitriding (Future Sales)
Brazing (Future Sales)
Powdered Metal Sintering (Future Sales)
Casting/Drawing (Future Sales)
Integral Atmosphere Production Units Ready for Order
Improved Atmosphere Recovery Prototype Ready for Trial
Corporate Demonstration Sites Wanted