Whilst reading up about the ZS EV on the Speak EV website, someone had posted a news article which mentioned that SAIC-GM were using a new process regards to corrosion prevention:

May 18, 2017 Düsseldorf / Germany

Henkel zirconium-based pretreatment solution drives technology upgrade

Setting New Benchmark: Henkel Helps SAIC-GM Make New Technological Breakthrough

Henkel Asia-Pacific announced that its automotive team had used Bonderite M-NT 1820 surface pretreatment technology to help SAIC General Motors Corporation Limited (known as SAIC-GM, a joint venture between General Motors Company and SAIC Motor) upgrade its car coating line.

The paint shop at SAIC-GM’s Jinqiao South plant, opened in 2003, used to employ Henkel’s traditional zinc phosphating pretreatment process to handle 300,000 units of passenger vehicles annually, including many premium models such as Buick Regal, Buick LaCrosse and Cadillac ATS-L. In May 2016, with full technology support from Henkel China, the paint shop upgraded its pretreatment process with zirconium thin film treatment which went into mass production merely after a one-week commissioning.

Kevin Cunningham, Pretreatment & Elpo Global Subject Matter Expert at General Motors, said to Terry Giles, Business Development Manager of Henkel Surface Treatment Global, “This upgrade is a success across Asia and will be viewed as a benchmark for future development by peers in the automotive manufacturing industry.”

Currently, almost all automotive OEMs are using traditional phosphating treatment processes. With their high-energy consumption, their use of heavy metals, and their creation of substantial solid and liquid waste streams, these processes are increasingly running up against ever-stricter environmental requirements. With a trend of more environment-friendly, cost-effective, high-quality and user-friendly pretreatment technology, Henkel launched Bonderite M-NT 1820 thin film pretreatment, a revolutionary technology that is viewed as an alternative to the traditional phosphating pretreatment. This ground-breaking solution will redefine the surface pretreatment technology in the automotive industry and set new standards for automotive manufacturers.

Bonderite M-NT 1820 surface pretreatment technology, as an alternative to traditional phosphating and passivation treatment, not only allows the treatment to coating process to be undertaken at room temperature without heating, but also fits all metal substrates, thus greatly shortening the process time and saving cost in equipment investment and process control. With Bonderite M-NT 1820, heavy metals, solid waste and waste water are all significantly reduced, thus saving resources and waste treatment cost. Since the processes of surface conditioning and passivation can be skipped, investment in process and equipment footprint are saved and the operational cost including water, electricity, gas and chemicals are reduced. With its excellent performance and strong capability of waste treatment and energy conservation, the Bonderite thin film technology has demonstrated high additional value to Henkel customers.

As a global leading supplier of automotive surface treatment products, Henkel is committed to green and energy efficient sustainable development and has never forgotten its social responsibility – to create more value for customers while helping them reduce environmental footprint. In 2016, Henkel won SURCAR Award for Environmental Footprint for the paint shop application of its Bonderite thin film pretreatment technology in passenger vehicle coating. The prize marks another milestone for Henkel in its pursuit of sustainable development.

Henkel is committed to developing solutions with cutting-edge technologies for automotive coating. Henkel is currently the leading service provider in the Chinese market to help customers renovate their outdated production lines by upgrading technologies, reducing the customer carbon footprint.

Source URL:

www.henkel.com/press-and-media/press-releases-and-...8

From the above statement, if SAIC are using the exact same process then it looks like they don't actually galvanise their bodyshells but use a film process instead.

The process does require that the actual bare metal itself is of good quality to begin with.