Zn and Sn in brasses and bronzes 3

[RylEnfield]

Dear all

I am in the middle of selecting either a brass or bronze for a pressure /wear situation the pressure is around 350 Lb and the relative movement between the two is for a very short tine

I am wondering what the roles of Zn and Sn play when added for example if I choose a bronze with 40% Zn does it have a better load carrying capability than bronze with only 20% Zn

What does Sn add to the mix ??
Kind regards in advance

Stephen

 

[metengr]

Typically, brass alloys are copper base that can contain up to 40% weight percent zinc. Zinc, as an alloying element, strengthens the copper matrix (called alpha phase) and over 35% content will form a second solid solution called Beta phase (zinc rich) - a two phase structure. The appearance of the beta phase increases hardness and strength of brass. Small additions of tin are used to increase resistance to a corrosion problem with certain brass alloys called dezincification, and to increase strength. If the brass contains less than 15% Zn this corrosion problem will not happen. The copper-zinc matrix can be alloyed with manganese and tin to form manganese bronze alloys.

Bronze alloys contain copper and of course tin as the primary alloying element. The strengthening affect of bronze comes into play with other alloy additions like iron, manganese and aluminum or silicon to form aluminum bronzes.

Before getting into detail regarding the pros and cons of a bronze or brass alloy, what is your specific application?
Will there be lubrication?
Approximate service conditions (temperature/environment)?

 

[RylEnfield]

Hi there is for clutch plates in a friction disc multi plate clutch, oil cooled the chain just dipps into the oil but the plates are not submersed

Spring pressure 350 psi total


kind regards for a great answer

stephen

 

[metengr]

Rylenfield;
Based on your description, I would probably use a phosphor bronze or manganese bronze alloy.

 

[RylEnfield]

That was on my list but I am worried about the heat and losss of Uts , the heat in the current unit can get to around 300 deg c , as the plates show signs of blueing... due to slippage
So we had do tuck a few more plates in there to avoid slip ...

Thank you kindly for your help

Stephen

 

[EdDanzer]

We have use Aluminum bronze in a low speed high torque brake application with good success.
Increasing the number of disks will not reduce slippage, only spread the heat over a greater area. To reduce slippage you must increase the pressure holding the disks together.