Some very interesting talking points... Except for the price. Wayne Gerdes – CleanMPG – Nov. 27, 2017 About the size of a dinner plate and thick as your thumb, the brake disc makes driving safer by significantly reducing stopping distances. There is another reason albeit little known reason why brake discs notoriety is coming to the forefront. It Is called “Brake Dust.” Most particulate emissions does not come from the internal combustion process but road, tire, and brake wear! I did not know this until a Bosch release brought it to my attention. According to a German environmental agency, brakes and tires are responsible for 32 percent of driving-related particulate emissions, roughly half of which is brake dust. Significantly reducing brake dust is essential to improving the air we breathe. A Bosch subsidiary, Buderus Guss, has developed the iDisc. Compared to a conventional brake discs, it generates up to 90 percent less brake dust! The unique selling point of the iDisc is a tungsten-carbide coating that is currently only available from Buderus Guss. Every year, the company produces up to 20 million discs. To transform a conventional disc into an iDisc, the friction rings are mechanically, thermally, and galvanically treated before being coated. All this is part of a process developed by Buderus Guss and Bosch researchers. In terms of price, the iDisc is approximately three times more expensive than a normal cast iron brake disc, and three times less expensive than a ceramic brake disc. The price is likely to fall as production volume increases. The iDisc is a simple drop in replacement to the conventional cast iron brake disc and could become the new standard. For cars alone, demand for brake discs are > 330 million worldwide in 2016 alone. Another argument in favor of the iDisc beyond the order of magnitude reduction in brake dust is that the carbide coating also ensures greater safety. The braking performance mimics that of a ceramic brake, especially when it comes to fading, as the reduction in stopping power following repeated braking maneuvers is known. Like a ceramic brake disc, the iDisc is highly stable in this respect and loses little deceleration performance. If you are driving hard enough to need ceramic discs, you do not give a damn about the environment… Wear is also significantly reduced. Depending on the strength of the carbide coating, the iDisc’s service life is twice that of a normal brake disc. Gouging marks on the friction ring? Not a chance. Corrosion is also not an issue – a major advantage, especially in electric cars. Because they recover braking energy, electric cars put less strain on the brakes and often must contend with rust formation on friction rings. The temporary slight decline in responsiveness during braking associated with this does not occur with the iDisc. A lot of puffery in this paragraph so keep that in mind. Another benefit is brake disc’s shiny carbide coating looks good, is wear-resistant, and corrosion-free. The 90 percent reduction in brake dust eliminates the need to regularly clean rims from brake dust residue. The iDisc is currently in production for a yet to be named European manufacturer.
Lessee, my Acura RSX has burned about 18.7 tons of gasoline over its lifetime and has lost maybe 10 or 20 grams of iron off the brake rotors and Bosch is claiming that my rotors produce more particulates than my engine? No wait. I'm reading it wrong. Bosch claims that road, tire, and brake wear account for more particulates than the engine. OK of those three my brake rotors account for maybe .00001%. Brake pads .0001%. Tires .001%. Tarmac and dirt road wear the rest.
We recently heard a study about injected gasoline engines that produce more particulates than filtered diesel engines. Which is far greater than we thought. So, I think these brakes are a good thing, but certainly not the biggest particle producing thing on a car. Also EV's and hybrids that are capable of strong regenerative braking already reduce brake dust by a lot.
I sometimes actively use the brakes (put the car in neutral going down a hill) to scrape off the rust. Non-rusting discs would be nice...
Your estimates are a bit off. "Non-exhaust sources account for 90% of PM10 and 85% of PM2.5 from traffic." - the research article From here, http://www.greencarcongress.com/2016/04/20160418-pm10.html and the research article here http://www.sciencedirect.com/science/article/pii/S135223101630187X The EV numbers are for a BEV. The authors assumed the regen braking would be zero for the analysis. It won't be on the road, but it seems no one has actually measured how much they actually reduce the particles from brakes. Hybrids will have higher amounts than plug ins because smaller batteries mean less regen. Tire and road wear depends upon the vehicle weight. Big batteries mean heavier cars. Resuspension is the dirt and dust on the road surface that is picked up and scattered by the vehicle's air wake. This is the study's weak point for BEVs. The research that has actually measured the amount of resuspension generally used regulatory classifications for vehicle types to describe the traffic population being studied. In most cases, these are weight based. Which leads to the conclusion that the resuspension amount is effected by vehicle weight, but it is how turbulent the air becomes under and behind the vehicle. Weight will have a part because, higher weight generally means larger tires to also kick up these particles, but it isn't the whole cause. In the traffic population on roads today, most of the heavier vehicles are going to be the less aerodynamic; the boxy work trucks and vans. The turbulence they create is going to be stronger than what a slippery BEV does, even if they are the same weight. So I think the EV resuspension amount is being overestimated by the study. The non-exhaust particle emissions are getting serious consideration to the point that vacuum systems near the brakes are being looked into. The DI particle emissions have been known for years. They don't already have exhaust filters in Europe because the EU gave them a wavier. Some port injected engines have even emitted enough particles that they should have filters under EU and US law. The EU will be starting to enforce the limits soon, which is why Toyota is using a hybrid direct and port injection system for their new engines. We'll just keep pretending gasoline cars have no particle emissions, and coal rolling diesel trucks are a greater evil than the more numerous riced out compact cars out there in the US though.
