1. Properties

The properties of platinum-rhodium alloy change regularly with the increase of Rhodium content:

(1) lattice constant and density decrease smoothly. (2) Increased mechanical properties. Due to

the stability of component properties and structure, platinum-rhodium alloys have very stable

mechanical properties at high temperature, especially those with rhodium content less than

25%. (3) With the increase of resistivity, the resistance temperature coefficient decreases.

(4) The thermoelectric potential and its stability increase, but the stability decreases when the

alloy is polluted. (5) Rhodium can reduce the volatilization loss of platinum in the alloy when

heated in high temperature oxidation atmosphere. (6) Enhanced acid corrosion resistance,

alloy containing more than 20% rhodium is insoluble in aqua regia. (7) platinum-rhodium alloy

has high catalytic activity. (8) platinum-rhodium alloy is generally easy to process, but the high

Rhodium alloy has low plasticity, so it has to be cogging down by hot working.

2. Application

High melting point, excellent chemical, mechanical and thermoelectric stability as well as high

catalytic activity, determine that platinum-rhodium alloys are more widespread and important

than any other noble metal alloys for industrial applications. Mainly used for: (1) thermocouple

manufacturing. PtRh10/Pt thermocouple is the most accurate temperature measurement above

300℃, is also 630.74 ~ 1064.43℃ in the temperature area of the international temperature benchmark,

generally measured temperature up to 1350℃(short time up to 1600℃); PtRh30/PtRh6,

PtRh13/Pt, PtRh20/PtRh5, PtRh40/PtRh20 and other thermocouples can measure higher

temperatures. (2) in the glass industry, it is used to make crucible, leakage plate, agitator,

electrode and other heat resistant and corrosion resistant devices. (3) as a catalyst in

ammonia oxidation and many other reactions. (4) as a high temperature heating body,

in which the furnace with PtRh40 alloy as heating body can work in the oxidation

atmosphere to 1800℃. (5) In the instrument industry used as electrical contacts, spark plug

electrode and potentiometer winding material. Typical platinum-rhodium alloys are PtRh3.5,

PtRh7, PtRh10, PtRh25 and PtRh40, of which PtRh10 is known as the "standard alloy" and

is the most widely used.

3. Properties of PtRh30

Density: 17.61 g/cm3

Tensile Strength: ＞480 Mpa

Resistivity at 20℃：19.00 μ Ω·cm

Vickers Hardness: ＞ 250 HV

Melting Point: 1927 ℃

4. Chemical Composition:  ( % )

Pt   70±0.5  Rh  30±0.5     Pd＜0.0005    Ir＜0.0005    Ag＜0.0003     Au＜0.0005  

Fe＜0.0005   Ni＜0.0005    Al＜0.0003    Pb＜0.0008   Mg＜0.0002    Si＜0.001

Ti＜0.0003    Cr＜0.0003   Cu＜0.0003     Mn＜0.0002