If you are having trouble viewing this email,
click here to display it in your web browser.

New NOCOLOK® Location in Garbsen, Germany

In autumn 2014, Solvay acquired Flux Schweiß- und Lötstoffe GmbH (Flux), which is now part of the GBU Special Chemicals. Both Solvay and Flux thus complement their product ranges and their expertise. The products will be marketed under the internationally known brand NOCOLOK®.

The Solvay Flux GmbH in Garbsen offers powders, suspensions, pastes and aluminium wires and rings, individually optimized for customers’ manufacturing processes, allowing for quick and precise positioning of the connecting components at the required brazing joints.

The Solvay Flux GmbH headquarters and production facilities are located in Garbsen, near Hannover. Forty employees work in the areas of research, management and marketing. Claudia Schreeck (see presentation below) and Werner Schmitt are the Managing Directors. Solvay Flux maintains representative offices and storage facilities worldwide to support customers locally for example in the United States and China.

Solvay Flux products

  • Corrosive flux as powder or paste: for difficult geometries and high magnesium and/or copper contents
  • Additional products for brazing: Green-Filler-Stop (see article below), wetting agents
  • Product group adhesive flux coatings for selective coating applications for "selective" brazing by coating the surface of heat exchanger parts by spray or roller

Monterrey Brazing Seminar 2014

Recognizing the incremental growth and maturity of the Mexican aluminium brazing market, we launched the first Solvay hosted aluminium brazing conference in Monterrey, Mexico.

Together with a selected group of supporting technology companies, we collaborated to give the industry solutions and information to assist them in their practice.

Congress Invitation

Invitation to the 4th International Congress and Exhibition on Aluminium Heat Exchanger Technologies for HVAC&R.

On 11 – 12 June 2015, the 4th International Congress will be again organised by DVS – German Welding Society and will take place at the Radisson Blu Scandinavia Hotel, Düsseldorf. The NOCOLOK® Team is taking part and we cordially invite you to attend this 2-day-event, where expert authors will present papers about aluminium heat exchanger technologies.

Stringent environmental requirements for increasing energy efficiency and reducing emissions are the greatest challenges the heating, ventilation, air conditioning and refrigeration industry faces. The Congress and Exhibition is dedicated to these challenges. This is an event for producers and users in the field of air conditioning and refrigeration.

You can find more information, registration and hotel reservation on the website.

New in the NOCOLOK®-Team

Last autumn, Solvay acquired the Flux- und Lötstoffe GmbH (Flux) (see NOCOLOK® News 4-2014). The company, now named Solvay Flux GmbH, is part of the Global Business Unit (GBU) Special Chemicals; headquarters and manufacturing facilities are located in Garbsen near Hannover.

One of the two CEOs of Solvay Flux is Claudia Schreeck. The qualified export executive, specializing in foreign languages, has been active for Flux since 1998 Flux, as Managing Director and co-owner since 2009.

Her current responsibilities at Solvay Flux include, among others, management and control of production and internal processes. "The merger has strengthened both sides. Solvay Flux GmbH offers products in the field of flux for brazing aluminium, tailored to our customers’ needs. Our advantages are high flexibility and short delivery times," says Claudia Schreeck.

In her limited spare time, the former handball player keeps fit with jogging and recreational sports. Football is also one of her great passions - but only as a spectator.

NOCOLOK® Quality from China

Since July 2014, the production of NOCOLOK® takes place in the Quzhou plant in east China. The joint venture of Solvay and Sinochem Lantian produced, several hundred tons NOCOLOK® for the Chinese market in 2014.

Numerous tests and investigations confirm the exceptional quality of the flux for brazing aluminium from China. Solvay has a unique worldwide quality standard, which laboratory tests confirm from the productions in Bad Wimpfen, Germany, Onsan, South Korea and Quzhou, China. All controlled measured values are well within the green range.

"Our customers in China are delighted with the consistently high quality of our flux," says Werner Schmitt, GBU Key Account Manager. Since the start of 2015, some 1st tier companies already validated counts as one of the Solvay-satisfied customers in China.

Flux-Green-Filler-Stop –
This far, but no further

Flux-Green-Filler-Stop (GFS) “stops” molten brazing filler metal from flowing into areas where it is unwanted, thus the surfaces remain clean and free from the presence of any filler metal.

Brazing filler metals do not like to bond with, or flow over, any dirt, grease, or oxides so the presence of any of such contaminants can prevent the filler metal from flowing over the surfaces of those parts to be brazed where these contaminants are located.

Therefore, GFS compounds are very effective at preventing molten filler metal flowing into protected areas. The GFS compounds are mixed with a liquid carrier solution and can be applied onto metal surfaces by using a small brush or by spraying or dipping.

For more information, please download the new brochure.

Restart for the NOCOLOK® Survey in 2015

Thanks for your votes last year! We are still working on the results. Your feedback overall is very positively in our favour.

We have decided to restart the NOCOLOK® survey in 2015, so do please give us your vote again.

We will be raffling a special prize among all the participants in 2015.

You can read more news about the prize in the next issue of the NOCOLOK® News.

Please give us your vote and, with a little luck, you will win the special prize!

Technical Article Flux Residue Part 2

Approach to non-corrosive fluxes for further reduced residue solubility and improved magnesium tolerance. Technical Information by Ulrich Seseke-Koyro, Hans-Walter Swidersky, Leszek Orman, Andreas Becker, Alfred Ottmann

Improved Magnesium tolerance

Mg additions to Al alloys contribute to higher strength properties. The ongoing trend in saving weight by down-gauging of Al sheet thickness requires sufficient mechanical stability. One option for the production of higher strength Al alloys is to increase the Mg content.

A disadvantage of Mg is the interaction with potas-sium fluoroamuminate fluxes during brazing, which results in poor joint formation [3] [4]. This effect, known as “flux poisoning”, is caused by the formation of high melting compounds. The addition of caesium and other metals to the flux helps to compensate to a certain degree the poisoning [6].

For the first set of laboratory brazing experiments we chose commercially available AMAG 6951 brazing sheet (0.68% Mg, 4343 clad) and clad-less AMAG angle material (0.68% Mg) to investigate the brazing performance and joint formation. In this situation the metal-to-metal interface adds up to 1.36% Mg (2 x 0.68%) in total.

Table 1 shows a list of representative flux combina-tions with NOCOLOK® types, KAlF4, Li3AlF6. CsAlF4, and AEFs.

We repeated all brazing tests with each sample three times.


Table 1: Brazing trials: AMAG clad – AMAG clad-free angle different flux blends based on KAlF4 plus BaF2/Li3AlF6/CsAlF4

The angles from most of the AMAG specimens could be removed after brazing by pulling. Only a broken inner and outer fractured seam line was left – as can be seen below in picture 1 a.


Picture 1: a) Photos, b) and c) SEM/EDX of NOCOLK® Cs Flux brazed sample
(load 15 g/m²) Coupon 0.68% Mg, angle 0.68% Mg – angle removed by pulling.

From the SEM analysis it is evident that a proper met-allurgical joint between base and angle has not been formed.


Picture 2: SEM/EDX analysis of aluminium ‘angle on coupon‘ brazed with KAlF4/BaF2 blend

There is flux residue present in the pulled apart fillet. This indicates that the liquid filler alloy was not capa-ble of pushing out completely the flux of the joint and it could be an explanation for the weakness of the fillet.

However, in case of the blend MD001212 LiCs24 with load 15g/m² the joint structure is thorough as can be seen in picture 3 a).


Picture 3: Microstructures of the brazed joints
a) Flux MD001212, load 15g/m²
b) Flux MD001223, load 15g/m²

It is worth mentioning when connecting blocks are brazed to condenser manifolds often a high load of manually applied flux is used in order to overcome the high Mg content in the block material. For such a case using the mixture MD001212 would allow for having quite high Mg content in the block material, which can be required by the designers of condens-ers.

The total concentration of 1.36% Mg (joint interface) is probably too high, because for most brazing applica-tions, a flux load of 15g/m² is impractical. Thus, we decided to reduce the level of Mg in our samples to half – i.e. to 0.68% – by switching to an AA1050 (Al 99.5%) angle. We also reduced the flux load to a more process-typical level of 5g/m². The results are listed in table 2:


Table 2: Brazing tests AMAG coupon (0.68% Mg)/Al99.5 angle

The structure of the joint cross section below (picture 4) obtained with flux MD001212 LiCs24 shows good quality.


Picture 4: Joint cross sections of alloys containing 0.68% Mg brazed with MD001212 LiCs24, load 5g/m²

Summary

Our research activities so far have been focusing on flux blends with additives to validate lower water solubility of post braze flux residue. Another objective of this work was to allow for brazing of Al alloys with increased Mg levels using non corrosive fluxes.

First steps have been made with selected flux blends. This paper reflects the current project status, but more work still needs to be done for further improvement.

Low flux residue solubility

It has been shown that the flux residue water solubility is reduced by combining KAlF4 with AEFs (“KAlF4 compound concept”); among them BaF2 being the most promising candidate.

Fluxes for higher Mg tolerance

Flux blends containing KAlF4 plus CsAlF4 and Li3AlF6 seem to be a promising approach to improve brazing of higher Mg containing aluminium alloys.

Aluminium coupons samples (AMAG 6951 with 0.68% Mg) for the base coupon and the angle (1.36% Mg in the joint interface) require flux loads as high as 15g/m² for successful brazing.

Good joint formation can be achieved at 5g/m² load on samples with 0.68% Mg content. Thus brazing of higher Mg level Al-alloys with appropriate flux mixtures at process-typical loads seems to be feasible.

Outlook

For the continuation of this project, we need to define the Mg range for real industrial aluminium heat exchanger needs. We think that this can best be done in a joint effort of HX manufacturer, Al material supplier and flux producer.

  1. P Garcia et al, Solubility Characteristics of Potassium Fluoroaluminate Flux and Residues, 2nd Int. Alum. Congress HVAC&R, Dusseldorf (2011)
  2. P Garcia et al., Solubility and Hydrolysis of Fluoroaluminates in Post-Braze Flux Residue, 13th AFC Holcroft Invitational Aluminum Brazing Seminar, Novi (2008)
  3. J Garcia et al, Brazeability of Aluminium Alloys Containing Magnesium by CAB Process Using Cs Flux, VTMS5, 2001-01-1763 (2001)
  4. H Johannson et al, Controlled Atmosphere Brazing of Heat Treatable Alloys With Cesium Flux, VTMS6 C599/03/2003 (2003)
  5. Handbook of Chemistry and Physics; Ref. BaSO4: 0.0025 g/l
  6. U Seseke, Structure and Effect – Mechanism of Flux Containing Cesium, 2nd Int. Alum. Brazing Con., Düsseldorf (2002)

NOCOLOK® NEWS

Presents information for NOCOLOK® users.

Publisher:
Solvay Fluor GmbH
Hans-Böckler-Allee 20 • 30173 Hannover, Germany

Place: Hannover
Register: Hannover HRB 58647

Managing Directors: Horst Kröger, Dr. Johannes Eicher

E-Mail: nocolok@solvay.com

Editorial:
Solvay Fluor GmbH
Department SFLU-RBUSI
E-Mail: hans.swidersky@solvay.com

Production:
Ahlers Heinel Werbeagentur GmbH, Hannover
www.ahlersheinel.de
nocolok@ahlersheinel.de

NOCOLOK® is a registered Trademark of Solvay Fluor GmbH

All statements, information, and data given herein are believed to be accurate and reliable but are presented without guarantee, warranty or responsibility of any kind, express or implied. Statements or suggestions concerning possible use of our products are made without representation or warranty that any such use is free of patent infringement, and are not recommandations to infringe any patent. The user should not assume that all safety measures are indicated, or that other measures may not be required. In any case, the user is not exempt from observing all legal, administrative and regulatory procedures relating to the product, personal hygiene, and protection of human welfare and the environment.