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Brazing Pastes
The basis for Fusion’s industry changing brazing pastes is a unique carrier binder system. This holds a finely atomised filler metal, and in some cases an oxide removing proprietary flux, in a stable suspension.
These binders are specifically formulated to ensure optimum characteristics regardless of the application method or brazing process. Our binder systems fall into two main groups: ‘fluxless’ and ‘fluxed’ binder carrier systems.
Fluxless binder systems for brazing paste
Fluxless binder systems are primarily utilised in a variety of brazing furnace operations. However, they also can be tested in select flame or induction systems depending on the context.
Applications where a fluxless system may be implemented include:
- atmospheric furnace
- vacuum furnace
- open air (when paired with a self-fluxing phos-copper alloy)
- flame when used with gas flux
- in a special induction machine containing an atmospheric chamber
Fusion offers a diverse portfolio of fluxless binder systems optimised for a variety of application methods (e.g. machine dispensing, dip/roll coat, stencil, squirt bottle) and “staged properties” (i.e. adhesion, slump, dry time).
Further advantages of fluxless brazing paste systems include their potential for higher alloy loading than traditional fluxed paste systems, which helps to minimise residue in furnace applications.
For more details of Fusion’s fluxless binder brazing paste systems, and the appropriate conditions for various applications, please contact us.
Fluxed binder carrier systems
The key ingredient in Fusion’s fluxed binder system is a proprietary flux. The role of this flux is to remove surface oxides and prevent reoccurrence of filler and base metal oxidation during open air brazing applications.
Industry standards dictate the performance criteria and include general chemical family requirements which often impact activation temperatures and residues. However, the flux itself remains a proprietary formulation.
The table in our brochure provides a starting point for identifying the flux required to properly join base materials based on their composition and the filler metal selected for the joint.
Fluxed binder systems incorporate a variety of fluxes as well as the brazing filler metal in suspension. These binder systems are optimised for Fusion’s automated dispensing systems, providing the benefit of improved application consistency.
Although we offer a wide variety of fluxed binder systems, our technical team can make minor modifications to customise each system for a customer’s specific application requirements. As such, the physical properties of each binder system can vary to ensure optimum results for a variety of factor,s including joint design, fliler metal composition/loading, part fixture orientation, brazing process, and temperature constraints.
Since brazing fluxes are composed of chemically active – and often corrosive – materials, their post-braze residue should typically be removed to minimise corrosion issues and ensure joint integrity.
For more details of our most common fluxed binder brazing paste systems, and the appropriate conditions for various applications, please contact us.
Silver Brazing Filler Metals
| Silver Brazing Alloys (BAg) | Specifcations | ||||||||||||||||
| Fusion Number | Ag | Cu | Zn | Cd | Ni | Sn | Solidus Temperature |
Liquidus Temperature |
AWS A5.8: 2019 |
AMS | ISO 17672:2016 | EN 1044:1999 |
|||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1076 | 42 | 33 | – | – | – | 25 | 560°C | 580°C | – | – | – | – | |||||
| 1115 | 60 | 30 | – | – | – | 10 | 602°C | 718°C | BAg-18 | 4773 | AG160 | AG402 | |||||
| 1202 | 40 | 30 | 28 | – | – | 2 | 649°C | 710°C | BAg-28 | – | AG140 | AG105 | |||||
| 1204 | 45 | 27 | 25 | – | – | 3 | 646°C | 677°C | BAg-36 | – | AG145 | AG104 | |||||
| 1205 | 56 | 22 | 17 | – | – | 5 | 618°C | 652°C | BAg-7 | 4763 | AG156 | AG102 | |||||
| 1206 | 60 | 24 | 14 | – | – | – | 682°C | 718°C | – | – | – | – | |||||
| 1246 | 45 | 25 | 30 | – | – | 25 | 680°C | 700°C | – | – | – | – | |||||
| 1255 | 55 | 21 | 22 | – | – | 2 | 630°C | 660°C | – | – | AG155 | – | |||||
| 1260 | 50 | 20 | 28 | – | 2 | – | 660°C | 707°C | BAg-24 | 4788 | AG450 | – | |||||
| 1265 | 25 | 41 | 32 | – | – | 2 | 688°C | 779°C | BAg-37 | – | AG125 | AG108 | |||||
| 1400 | 72 | 28 | – | – | – | 25 | 779°C | 779°C | BAg-8 | – | AG272 | AG401 | |||||
| 4765 | 56 | 42 | – | – | 2 | – | 771°C | 893°C | BAg-13a | 4765 | AG456 | – | |||||
| 4774 | 63 | 28.5 | – | – | 2.5 | 6 | 691°C | 802°C | BAg-21 | 4774 | AG463 | – | |||||
By definition, a brazing filler metal has a liquid temperature greater than 840°F, but lower than that of the base metal(s) being joined.
Fusion paste brazing filler metals are classified based on their primary metal alloy composition. These filler metals can be paired with a Fusion flux containing or fluxless binder system depending on the brazing process.
The most common categories of industrial use compositions include Silver Brazing Filler Metals, Copper/Copper Alloy Filler Metals, Nickel Filler Metals, Gold Filler Metals, and Aluminum Filler Metals. The below sections explain the primary applications and attributes for common Fusion industrial filler metals.
As with all brazing/soldering applications, the joint configuration, design requirements, and process conditions may impact the joint integrity and dictate specific filler metals.
Please contact your Fusion Representative to help identify the proper product.
Silver Brazing Filler Metals (BAg)
Silver bearing pastes are among the most widely used structural fller metals. These may be used to braze most ferrous and non-ferrous base metals, excluding aluminium, titanium, and magnesium. They have become popular due to their free-flowing, ductile nature and relatively low melting range.
All conventional heating methods may be used with the silver-bearing brazing pastes, however, the process conditions and part design can influence the alloy/flux/binder combination best suited for the project. In general, open air brazing (torch, induction, resistance) is easily accomplished using a proprietary Fusion flux binder system with all silver alloys.
Silver brazing in atmospheric furnaces require extremely low dew points to obtain appropriate wetting. Zinc and tin containing silver alloys are often avoided in vacuum brazing due to volatilisation of those constituents.
Copper-Bearing Filler Metals
| Copper Brazing Alloys (BCu) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fusion Number | Cu | Cu2O | Fe2O3 | Solidus Temperature |
Liquidus Temperature |
AWS A5.8: 2019 |
ISO 17672:2016 | EN 1044:1999 |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| G1900F | 100 | – | – | 1083°C | 1083°C | BCu-1a | CU 099 | CU 103 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Fusion Copper (BCu)
Copper filler metals and their alloys are an economical option for many applications. Pure copper brazing alloys are extremely free-fowing and exhibit excellent strength properties. In fact, some pure copper joints approach the strength of the parent metals themselves.
The addition of various oxides (copper oxide and iron oxides) can somewhat restrict the free-flowing nature of pure copper filler metals, while improving the ability to fill joint gaps.
The high temperatures required for pure copper brazing often requires the use of a reducing atmosphere or vacuum, so these filler metals are commonly paired with a fluxless binder system for use on steel and stainless steel base metals. The table below outlines Fusion’s common copper and copper-oxide fller metals.
| Phos/Copper Alloys (BCuP) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fusion Number | Cu | P | Ag | Other | Solidus Temperature |
Liquidus Temperature |
AWS A5.8: 2019 |
ISO 17672:2016 | EN 1044:1999 |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1190 | 75 | 7.25 | 17.75 | – | 643°C | 644°C | – | – | – | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1300 | 92.75 | 7.25 | – | – | 710°C | 793°C | BCuP-2 | CuP 181 | – | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1306 | 86.75 | 7.25 | 6 | – | 643°C | 718°C | BCuP-4 | CuP 283 | – | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1310 | 86.25 | 6.75 | – | 7 Sn | 640°C | 680°C | – | – | – | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1315 | 80 | 5 | 15 | – | 643°C | 802°C | BCuP-5 | CuP 284 | CP 102 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1320 | 91.75 | 8.25 | – | – | 710°C | 716°C | – | – | – | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Phos-Copper (BCuP)
The addition of phosphorus to a copper-based alloy (known as Phos-Copper Alloys or designated as BCuP alloys) has been known to offer “self-fuxing” properties when used on copper base metals. These BCuP fller metals, however, should not be used on steel or nickel base metals due to the possibility of Phosphorus Embrittlement – a weakening condition created by base metal / filler metal interactions.
| Other Copper Alloys (Brass and Bronze Alloys) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fusion Number | Cu | Mn | Ag | Zn | Other | Solidus Temperature |
Liquidus Temperature |
AWS A5.8: 2019 |
ISO 17672:2016 | EN 1044:1999 |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1440 | 27.5 | – | – | 65 | 7.5 Sn | 751°C | 782°C | – | – | – | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1650 | 55 | .25 | – | 44.75 | – | 877°C | 890°C | – | – | – | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1664 | 60 | – | – | 39.7 | 0.3 Si | 875°C | 895°C | – | – | – | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1720 | 77.85 | 20 | – | – | 2.15 Ni | 920°C | 950°C | – | – | – | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Copper Zinc (Brass) and Copper Tin (Bronze) Filler Metals
When copper is combined with zinc (Brass) or tin (Bronze), the resulting alloys create an economical method for joining both ferrous and non-ferrous base metals at temperatures lower than pure copper braze joints. These brazing filler metals have wide application uses in industry, however, testing should be conducted on the finished part as the addition of zinc and tin may decrease the resistance to corrosion and increase the chance for stress corrosion cracking.
Nickel Brazing Filler Metals
| Nickel Brazing Alloys (BNi) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fusion Number | Ni | Cr | Fe | Si | B | P | Other | Solidus Temperature |
Liquidus Temperature |
AWS A5.8: 2019 |
AMS | ISO 17672:2016 | EN 1044:1999 |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1610 | 89 | – | – | – | – | 11 | – | 877°C | 877°C | BNi-6 | – | Ni 700 | NI 106 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1630 | 75.9 | 14 | – | – | – | 10.1 | – | 888°C | 888°C | BNi-7 | – | Ni 710 | NI 107 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1633 | 60.5 | 29.5 | – | 4 | – | 6 | – | 970°C | 1030°C | BNi-15 | – | – | – | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 4775 | 73.15 | 14 | 4.5 | 4.5 | 3.1 | – | 0.75 | 977°C | 1038°C | BNi-1 | – | – | – | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 4776 | 73.9 | 14 | 4.5 | 4.5 | 3.1 | – | – | 977°C | 1077°C | BNi-1a | 4776 | Ni 610 | NI 1a1 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 4777 | 82.4 | 7 | 3 | 4.5 | 3.1 | – | – | 971°C | 999°C | BNi-2 | 4777 | Ni 620 | NI 102 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 8100 | 70.87 | 19 | – | 10.13 | – | – | – | 1079°C | 1135°C | BNi-5 | 4782 | Ni 650 | NI 105 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Fusion Nickel-Bearing Filler Metals (BNi)
Nickel brazing filler metals provide a variety of benefits including excellent strength and corrosion resistance both at elevated temperatures and in other harsh environments.
Depending on the specifc composition, nickel-bearing alloys can be resistant to service temperatures up to 1800 °F (980°C) and provide improved resistance to oxidation and corrosion for a variety of base metals, both ferrous and non-ferrous in nature.
Although the best results are obtained by vacuum brazing or other furnace type, alternate heating methods can be used with the addition of an appropriate flux.
Process application is critical when selecting the appropriate nickel filler metal. Boron containing filler metals are sensitive to nitrogen containing atmospheres as the boron has a strong affnity for nitrogen and can create a compound which inhibits braze fow (i.e. boron nitride). These boron containing filler materials should therefore be run in either vacuum, pure dry hydrogen, or argon furnace with a dew point of -60F or better for best results.
The non-boron containing nickel filler metals, such as BNi-5, BNi-6 & BNi-7, can produce acceptable results in a nitrogen containing atmosphere assuming the atmosphere quality is good (-60F dew point). Nickel-bearing filler metals are most commonly used to braze stainless steel (300 and 400 Series), nickel, and cobalt-based alloys, however, they can be used on a variety of both ferrous and non-ferrous parent materials.
The table above outlines some of the most common nickel filler metals offered by Fusion.
Aluminium Filler Metals (BAlSi)
| Fusion Number | Al | Zn | Si | Cu | Description | Solidus Temperature |
Liquidus Temperature |
AWS A5.8: 2019 |
AMS | Aluminum Association |
ISO 17672:2016 | EN 1044:1999 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1070 | 88 | – | 12 | – | General purpose aluminum brazing alloy common for most brazing applications including heat exchangers. | 577°C | 582°C | BAlSi-4 | 4185 | 4047 | Al 112 | AL 104 |
Aluminium Brazing with Induction
Tight control of aluminium brazing applications is crucial as the melting temperatures of the brazing alloy and aluminium base metals can be very similar. Induction brazing offers advantages over torch and furnace methods, including reduced operator skill requirements, lower energy costs, smaller equipment footprint, and improved quality in lean manufacturing processes.
Other benefits include precise localized heating for tight production tolerances, faster heating cycles for increased production rates, consistent and repeatable heating for reduced defect rates, consistency across operators and shifts, and preservation of metallurgical characteristics.
Common in the automotive industry, induction brazing is used for various parts such as tubes and brackets assemblies. Fusion can provide complete tailored brazing pastes with optimised binder/flux systems for your induction brazing application.
For inquiries, contact our Technical/Sales Team at tel. 01279 443 122 or email infoeurope@fusion-inc.com.