VBC Group https://www.vbcgroup.com VBC Welding and Vacuum Brazing Products Tue, 13 Aug 2019 14:22:12 +0000 en-GB hourly 1 https://www.vbcgroup.com/wp-content/uploads/2018/09/vbc-favicon-150x150.png VBC Group https://www.vbcgroup.com 32 32 VBC Group – Building Relationships Across the Globe https://www.vbcgroup.com/2019/01/15/vbc-group-building-relationships-across-the-globe/ https://www.vbcgroup.com/2019/01/15/vbc-group-building-relationships-across-the-globe/#respond Tue, 15 Jan 2019 12:14:19 +0000 https://vbcgroup.com/?p=1 VBC Group will be at a number of upcoming events around the world to build future relationships by connecting the people, businesses, and organisations at these events.  Find out more below but please do get in touch for more information TCT Show – NEC, Birmingham (24-26th September 2019) VBC additive is thrilled to announce that…

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VBC Group will be at a number of upcoming events around the world to build future relationships by connecting the people, businesses, and organisations at these events.  Find out more below but please do get in touch for more information

TCT Show – NEC, Birmingham (24-26th September 2019)

VBC additive is thrilled to announce that they have signed a distributor agreement with Tekna. VBC is now the distributor of their AM powders to the UK and Ireland VBC Additive will be exhibiting at the highly anticipated TCT show in September.

Find us on Booth C32

We hope to see you there!

Singapore MRO Asia-Pacific  – Singapore Expo Convention and Exhibition Centre (24-26th September 2019)

VBC Group is launching their new office in Singapore as VBC Pte Ltd, this is an extremely exciting time for the company. VBC Pte Ltd will be exhibiting at the Singapore MRO Asia-Pacific.

Find us on Booth 926

We hope to see you there!

Events attended

May 21st – 23rd 2019

Eurogress Aachen
Monheimsallee 48
52062 Aachen
GERMANY

View event website >

Kuala Lumpur International Aerospace Business Convention

October 2nd – 4th 2018
Stand 8
View event website >

Singapore MRO

November 6th – 8th 2018
Stand 801
View event website >

Bahrain International Air Show

November 14th – 16th 2018
Stand D03
View event website >

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Active Braze Alloys https://www.vbcgroup.com/2018/10/01/active-braze-alloys/ https://www.vbcgroup.com/2018/10/01/active-braze-alloys/#respond Mon, 01 Oct 2018 14:43:25 +0000 https://vbcgroup.com/?p=1172 How it All Started Like many other innovations in science, the process of active brazing was reportedly discovered by accident.  During brazing trials an alloy containing a small amount of zirconium inadvertently flowed onto an alumina fixture during the more commonly used molybdenum manganese metallization method.  To the surprise of the engineer, the alloy wet…

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How it All Started

Like many other innovations in science, the process of active brazing was reportedly discovered by accident.  During brazing trials an alloy containing a small amount of zirconium inadvertently flowed onto an alumina fixture during the more commonly used molybdenum manganese metallization method.  To the surprise of the engineer, the alloy wet and bonded to the ceramic.  The zirconium was acting as the active element which allowed the braze alloy to wet the ceramic.  This realisation has changed the way we join ceramics today.

When to use Active Brazing

Active brazing is used when conventional brazing will not work.  This is typically with ceramic materials such as alumina, silicon carbide, sapphire, diamond and graphite.  Previously this type of material could only be brazed using the molybdenum manganese process whereby the surface of the components is metallized to prepare them for brazing in the standard manner.

While the Mo-Mn process is well established and widely used in some industries there are certain disadvantages to it.  These include the high cost and the fact that it is a time consuming multiple stage process.  This makes it unsuitable for small batches or development work.

Active brazing on the other hand is a straightforward single stage process. It uses braze alloy in foil, paste, wire or preforms to join ceramic to ceramic or frequently ceramic to metal usually in a vacuum furnace.  It forms a strong joint where the parent material usually fails before the braze joint.

So how does it work?

Many of the materials joined using active braze alloys are oxides or carbides.  Usually we are told that oxides must be removed before wetting can occur.  In the case of active braze alloys however a reaction takes place between the active element within the filler metal, usually titanium and the oxides, carbides or nitrides.  This forms titanium oxide, titanium carbide or titanium nitride which allows the filler metal to wet the surface of the ceramic.  Titanium is the most commonly used active element in commercially available braze alloys, though others such as hafnium, vanadium, zirconium and chromium are also active elements to a greater or lesser degree.  The nature of the intermetallic layer formed because of this reaction is determined by the concentration of the active element and the time/temperature parameters of the brazing cycle.  The incorrect cycle or alloy can result in a brittle intermetallic layer in the braze joint hence careful selection of both is critical.

What kinds of Active Braze Alloys are available?

There is an array of commercially available active braze alloys with brazing temperatures ranging from 700⁰C to over 1050⁰C. The compositions range from less than 1% active element, though 1%-4%  is more typical.  The majority of the alloys are silver and copper based but gold and nickel also feature strongly.  Indium is used in some alloys to reduce the brazing temperature of the alloy.  There is a suitable alloy for every application

What type of atmosphere is used?

As mentioned in a previous article the brazing atmosphere is crucial in achieving a sound joint.  Active brazing is best carried out in a vacuum where any oxygen is excluded to prevent the active element reacting prematurely with air.  Brazing in an inert atmosphere is also possible as long as the components being brazed are completely purged of air.  Remember both oxygen and nitrogen will react readily with titanium and therefore nitrogen, which is often used as a shielding gas, must not be used with titanium containing active braze alloys.

Ceramics to Metals

Applications for active brazing often require that a ceramic is brazed to a metal rather than another ceramic.  This has implications related to the difference in coefficients of thermal expansion of the different materials.  Ceramics are generally brittle with low CTE compared to the metals they are joined to.  This makes cracking of the ceramics a distinct possibility during the cooling stage of the braze cycle. Careful selection of the braze filler metal and design considerations can help mitigate against this.

Metal to Metal

Of course active braze alloys are also very useful in brazing metals, most notably stainless steels.  The property that makes stainless steel corrosion resistant is the chromium oxide layer which protects it.  This oxide layer is easily dealt with by the active braze alloy.   Active brazing alloys also permit effective wetting of stainless steels and refractory materials such as tungsten carbide.

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Inert and Reducing Gases used in Induction Brazing https://www.vbcgroup.com/2018/10/01/inert-and-reducing-gases-used-in-induction-brazing/ https://www.vbcgroup.com/2018/10/01/inert-and-reducing-gases-used-in-induction-brazing/#respond Mon, 01 Oct 2018 11:40:40 +0000 https://vbcgroup.com/?p=1166 You may instinctively associate VBC with Vacuum Brazing technologies but did you know we also technically support Induction brazing? Induction brazing is an efficient and clean method of joining metallic and ceramic components which can be carried out in air but there are further benefits to be obtained when brazing in inert or reducing atmospheres.…

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You may instinctively associate VBC with Vacuum Brazing technologies but did you know we also technically support Induction brazing?

Induction brazing is an efficient and clean method of joining metallic and ceramic components which can be carried out in air but there are further benefits to be obtained when brazing in inert or reducing atmospheres.

The benefits of induction brazing in a suitable atmosphere over vacuum brazing include significantly reduced capital investment, much faster heating cycles, localised heating only which reduces the risk of distortion of parts and removing the need for fluxes.

Parts that are brazed using this method avoid risks of oxidation if the correct gas and set up is used.  Fixturing plays an important part of the set up.  It must allow the gas to completely surround the brazed joint throughout the heating cycle to prevent oxidation.  Certain alloys, most notably the active braze alloys such as VBC Alloy 4033, a Silver/Indium based alloy used in brazing ceramics for example will not wet the surface if any oxygen is present.  The gas should flow over the part to remove any moisture and oxygen away from the joint.

It is often desirable to be able to see the braze joint up close during the braze cycle.  This is not possible in furnace brazing. With induction brazing quartz glass can be designed into the fixtures in the fixtures to allow the operator to see the braze flow.  Quartz glass is advisable especially if an optical pyrometer is to be used as the beam can be aimed at the part through the glass without any loss in accuracy of the temperature reading.  The induction coil can be inside or outside the glass, though keeping the distance between the coil and the work-piece to a minimum is preferred for maximum energy transfer.

There are two types of gases used in brazing, inert gases that inhibit oxidation and reducing gases that react with any undesirable films on the parts being brazed or the braze alloy and thereby remove them from the braze joint.

Oxidation is the formation of oxides on the surface of the metal when it reacts with the oxygen present in air.  These oxides may prevent the braze alloy from wetting the surface.  This reaction is enhanced when the metal is heated.

Atmospheres which inhibit oxidation are inert and their purpose is to purge the braze zone of any oxygen or other gases which may react with the metals being joined.   These atmospheres include argon and helium and mixes of either.

Nitrogen is sometimes used as a shielding gas and can be regarded as inert for most cases but it is not suitable for brazing titanium with which it forms titanium nitrides. Likewise titanium will react with hydrogen to form titanium hydrides.  For brazing titanium and its alloys argon or helium should be used with a Silver/copper based active braze alloy such as VBC Alloy 4011 for example.

Reducing atmospheres are chemically active and will react with surface contaminants on the parts or the braze alloy and will remove them from the braze joint.   Hydrogen is commonly used as a reducing gas and will reduce most metal oxides.

Occasionally a combined gas may be used, for example Nitrogen/Hydrogen or Hydrogen/Argon (Hygon).  Gases that are commonly used as reducing or deoxidising agents also include mixtures of nitrogen & hydrogen, nitrogen/methanol mixtures and argon or argon/hydrogen mixes.  The choice of gas will be determined by the materials being brazed, the required quality and the cost implications.

The dew point (or moisture content) of the gas is an important consideration as this will have a significant influence on which oxides will be reduced.  Ideally the dew point should be at a minimum as any water vapour will tend to cause oxidation.  One exception to this is when brazing carbon steels where some degree of moisture is required as the braze alloy can flow excessively otherwise.

A further benefit of induction brazing is that the rapid cool down cycle reduces oxidation.  In addition the brazed parts are usually cleaner and brighter after brazing in a reducing/deoxidising atmosphere.

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IBSC 2018 Conference https://www.vbcgroup.com/2018/10/01/ibsc-2018-conference/ https://www.vbcgroup.com/2018/10/01/ibsc-2018-conference/#respond Mon, 01 Oct 2018 10:24:01 +0000 https://vbcgroup.com/?p=1160 VBC’s Brazing Director Phil Webb and Technical Manager Pat Rodgers have just returned from the International Brazing and Soldering Conference 2018, organised by the American Welding Society and held in New Orleans. The conference itself was excellent, with cutting-edge research papers presented by leading companies in the brazing and soldering field. VBC sponsored Liam Hardwick,…

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VBC’s Brazing Director Phil Webb and Technical Manager Pat Rodgers have just returned from the International Brazing and Soldering Conference 2018, organised by the American Welding Society and held in New Orleans.

The conference itself was excellent, with cutting-edge research papers presented by leading companies in the brazing and soldering field. VBC sponsored Liam Hardwick, a PhD researcher based at the Universities of Sheffield and Manchester who gave an excellent presentation.

The conference clearly showcased that the metal joining industry continues to develop at an extremely fast pace.

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Our Rebrand https://www.vbcgroup.com/2018/10/01/our-rebrand/ https://www.vbcgroup.com/2018/10/01/our-rebrand/#respond Mon, 01 Oct 2018 09:44:58 +0000 https://vbcgroup.com/?p=1176 We are proud to announce the launch of the new company logo as part of the ongoing evolution of our Company’s brand and the services we provide to our customers. What does this mean looking forward? Introducing a new logo and brand identity hasn’t altered our core values or vision, we feel it has made…

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We are proud to announce the launch of the new company logo as part of the ongoing evolution of our Company’s brand and the services we provide to our customers. What does this mean looking forward? Introducing a new logo and brand identity hasn’t altered our core values or vision, we feel it has made us stronger.

We are a modern, sophisticated, high-growth solution provider for High-Tech & Quality Critical Applications within the Brazing and Welding market, and we now have the branding to match. The fox represents the location of our UK Head Office in Loughborough, which is in the Midlands – the heart of UK industrial manufacturing. We’re experiencing incredible growth, we’re constantly innovating new product solutions and, more than ever, we’re committed to improving customer experience.

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