february 7, 2002 sme brazing and soldering technologies conference 1 new developments in brazing...

February 7, 2002 SME Brazing and Soldering Technologies Conference

1

NEW DEVELOPMENTS NEW DEVELOPMENTS IN BRAZING FLUXESIN BRAZING FLUXES

DR. Y. BASKINSME BRAZING AND SOLDERING TECHNOLOGIES CONFERENCE

ORLANDO, FLORIDAFEBRUARY 7-8, 2002


2

DEVELOPMENT OF A FLUORIDE-DEVELOPMENT OF A FLUORIDE-FREE FLUX WAS DRIVEN BY FREE FLUX WAS DRIVEN BY

ENVIRONMENTAL AND SAFETY ENVIRONMENTAL AND SAFETY CONCERNSCONCERNS

Cleaner Plant Water Effluents Better Workplace Air Quality Improved Safety in Brazing

Operations


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THE PAST DECADES HAVE THE PAST DECADES HAVE WITNESSED THE ELIMINATION WITNESSED THE ELIMINATION OF HAZARDOUS METALS AND OF HAZARDOUS METALS AND

CHEMICALSCHEMICALS Cadmium from brazing filler

metals Lead from plumbing soft-solders CFC solvents in all applications Hydrazine from different

formulations Asbestos from insulation


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PRIMARY REASONS FOR PRIMARY REASONS FOR CONTINUED USE OF FLUORIDE CONTINUED USE OF FLUORIDE

BEARING FLUXESBEARING FLUXES Fluoride-bearing brazing fluxes perform

consistently in many applications, giving little reason for change.

There was an almost universal conviction that it was impossible to develop an acceptable fluoride-free brazing flux, leading to little R&D efforts.

Environmental and health studies concentrated on other sources that exhibited greater dangers, such as CFCs, lead, and other elements.


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COMMON INGREDIENTS OF COMMON INGREDIENTS OF CONVENTIONAL BRAZING CONVENTIONAL BRAZING

FLUXESFLUXES Boric Acid Boron Oxide Elemental Boron Organic Additives Potassium Bifluoride Potassium

Fluoborate

Potassium Fluoride Potassium

Pentaborate Potassium

Tetraborate Silicon Dioxide Sodium Tetraborate Water


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COMPOSITIONAL AREA OF COMMON BRAZING FLUXES


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FLUX ACTIVATION TEMPERATURE AS A FUNCTION OF B/F RATIO


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EFFECT OF TIME ON FLUX ACTIVATION TEMPERATURE


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FLUX EXHAUSTION TEMPERATURE AS A FUNCTION OF B/F RATIO


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THE HAZARDS ASSOCIATED THE HAZARDS ASSOCIATED WITH FLUORIDE-BEARING WITH FLUORIDE-BEARING FLUXES CHANGE DURING FLUXES CHANGE DURING

DIFFERENT BRAZING OPERATION DIFFERENT BRAZING OPERATION STAGESSTAGES

Working with raw flux

Brazing at elevated temperatures when HF and BF3 gases are released

Discharging raw flux and flux residues into plant effluent, and entry into water system


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EXPOSURE LIMITS AND HAZARD EXPOSURE LIMITS AND HAZARD LABELS FOR FIVE FLUORIDESLABELS FOR FIVE FLUORIDES

FLUORINE ACGIH OSHA NIOSH OSHAD.O.T

COMPOUND TWA-TLV TWA-PEL TWA-REL LABELLABEL

Boron Trifluoride 1ppm 1ppm 1ppm -Poison

Hydrogen Fluoride 3ppm 3ppm 3ppm Toxic Corrosive

Potassium Bifluoride 2.5 mg/m3 2.5 mg/m3 2.5 mg/m3 Toxic Corrosive

Potassium Fluoborate 2.5 mg/m3 2.5 mg/m3 2.5 mg/m3

Toxic -

Potassium Fluoride 2.5 mg/m3 2.5 mg/m3 2.5 mg/m3 Toxic -


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POTENTIAL HEALTH HAZARDS POTENTIAL HEALTH HAZARDS FROM USE OF FLUORIDE-FROM USE OF FLUORIDE-

BEARING FLUXESBEARING FLUXES Irritation to skin and fingernails by the

raw flux. Irritation of the eyes, mucous membranes,

and respiratory system by gases and fumes generated during brazing.

Calcium depletion (sclerosis) of the bones and mottled teeth from long-term exposure to fluoride gases and fine fume particles.

Potential health hazards from discharge of untreated flux and flux residues into the water supply.


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EQUIPMENTEQUIPMENT

Thermolyne 1500 Furnace – Maximum Temperature: 1,200°C

Calibrated Pyrometer with Surface Probe. Maximum Temperature: 1,300°C

30 Tempilstik Temperature Indicators. Temperature Range: 400-1,200°C

Brookfield Viscometer Hot Plate Timer Balance


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BASE METALSBASE METALS

Copper

Mild Steel

Brass C-260 (70%Cu/30%Zn)


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FILLER METALSFILLER METALS

AWS LIQUIDUSCLASSIFICATION COMPOSITION

TEMPERATURE

BAg-28 40% Ag710°C/1,310°F

30%Cu28%Zn

2%Sn

BAg-36 45%Ag 688°C/1,270°F

27%Cu25%Zn3%Sn

BCuP-4 87.5%Cu 718°C/1,325°F

6%Ag7.25%P


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PHYSICAL PROPERTIES OF PHYSICAL PROPERTIES OF FLUORIDE-FREE FLUXFLUORIDE-FREE FLUX

Form Creamy PasteColor WhiteSpecific Gravity 1.4Viscosity @ 22°C/72°F 225,000 ± 20,000 cpsFluorine Content < 100 ppmFlash Point NoneFreezing Effects NoneHeating Effects to 50°C/122°F MinimalActive Temperature Range 670-870°C/1,235-

1,600°F


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TEMPERATURE RANGES FOR TEMPERATURE RANGES FOR FLUXES AND FILLER METALSFLUXES AND FILLER METALS

MAXIMUM ACTIVATION RECOMMEND

FLUX TEMPERATURE TEMPERATURE

Average Fluoride-Bearing 570°C/1,050°F 870°C/1,600°FFluoride-Free 670°C/1,235°F 870°C/1,600°F

MAXIMUMLIQUIDUS RECOMMENDED

FILLER METAL TEMPERATURE TEMPERATURE

BAg-28 (40%Ag) 710°C/1,310°F 802°C/1,475°FBAg-36 (45%Ag) 688°C/1,270°F 785°C/1,450°FBCuP-4 (6%Ag) 718°C/1,325°F 785°C/1,450°F


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FILLER METAL SPREAD AS A FILLER METAL SPREAD AS A FUNCTION OF BASE METAL AND FUNCTION OF BASE METAL AND

FLUXFLUXBASE FILLER METALSMETAL FLUX BAg-28 BAg-36 BCuP-4

Brass Fluoride-Free Excellent Excellent Excellent

Fluoride-Bearing Excellent ExcellentExcellent

Copper Fluoride-Free Moderate Moderate Moderate

Fluoride-Bearing Excellent Excellent Poor

Mild Steel Fluoride-Free Moderate Moderate Poor

Fluoride-Bearing Moderate Moderate Poor

FURNACE TEMPERATURE: 785°C/1,450°F TIME IN FURNACE: 60 SecondsEXCELLENT SPREAD: > 2.0cm2 MODERATE SPREAD: >0.5cm2<2.0cm2

POOR SPREAD: <0.5cm2


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BENEFITS OF USINGBENEFITS OF USINGFLUORIDE-FREE FLUXFLUORIDE-FREE FLUX

Greater Operator Safety

Better Workplace Air Quality

Cleaner Plant Water Effluents


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PRIMARY SKIN IRRITATION PRIMARY SKIN IRRITATION STUDYSTUDY

FLUORIDE-FREE FLUORIDE-BEARING

FLUX FLUX

Primary Dermal Irritation Index 2.3 5.9(PDII)

Classification Not a primary irritant. A primary irritant

Non-corrosive to skin. Corrosive to skin.


21

APPLICATIONS FOR APPLICATIONS FOR FLUORIDE-FREE FLUXFLUORIDE-FREE FLUX

COPPER-TO-COPPER

COPPER-TO-BRASS

COPPER-TO-MILD STEEL

BRASS-TO-BRASS

BRASS-TO-MILD STEEL

MILD STEEL-TO-MILD STEEL

february 7, 2002 sme brazing and soldering technologies conference 1 new developments in brazing...

Documents

brazing operations sme

insulationsme brazing

baskinsme brazing

raw flux brazing

mgm3toxicsme brazing

water systemsme brazing

brazing filler metals

fluoridefree flux