Sintered body comprising a plurality of materials and pressure measuring instrument comprising such a sintered body

Patent metadata

Field	Value
Publication number	US-9863831-B2
Application number	US-201414779582-A
Country	US
Kind code	B2
Filing date	Feb 17, 2014
Priority date	Mar 25, 2013
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A sintered body comprises a first region which comprises a first material having a first effective coefficient of thermal expansion α 1 , a second region which comprises a second material having a second effective coefficient of thermal expansion α 2 , a transition region between the first region and the second region in which the effective coefficient of thermal expansion changes from the first effective coefficient of thermal expansion to the second effective coefficient of thermal expansion. The transition region has a sequence of layers with a mixture of at least the first material and the second material, with the mixing ratio of the layers varying in order to achieve a stepwise, in particular monotonic, change in the coefficient of thermal expansion.

First claim

The invention claimed is:

1. A sintered body, comprising:
a first region which has a first material having a first effective coefficient of thermal expansion α 1 ;
a second region which has a second material having a second effective coefficient of thermal expansion α 2 ; and
a transition region between said first region and said second region in which the effective coefficient of thermal expansion changes from said first effective coefficient of thermal expansion to the second effective coefficient of thermal expansion, wherein:
said transition region has a sequence of layers with a mixture of at least said first material and said second material, with the mixing ratio of the layers varying in order to achieve a stepwise, in particular monotonic, change in the coefficient of thermal expansion;
said transition region has a maximum extension d vertically to one direction of the layer sequence, and said transition region has a height h in the direction of the layer sequence, whereby the following applies:

d
h

·



Δ
⁢

⁢
α



<
ξ

,

Δα is the difference between the first effective coefficient of thermal extension and the second coefficient of the thermal expansion, and wherein ξ is a constant with the dimension 1/K, for which the following applies: ξ <0.1%/K, especially <500 ppm/K, preferably <250 ppm/K, further preferred <125ppm/K and particularly preferred <60 ppm/K, whereby the following applies:

ξ
=

C

Δ
⁢

⁢
T

ΔT =(T max −T min ) is a size of a specified temperature range for the sintered body, and wherein C is a dimensionless deformation parameter, for which the following applies: C <4%, especially C <2% and preferably C <1%.

2. The sintered body according to claim 1 , wherein:
said layers substantially run parallel to each other.

3. The sintered body according to claim 2 , wherein:
said layers are substantially planar.

4. The sintered body according to claim 1 , wherein:
said first material is a ceramic material with a coefficient of thermal expansion of no more than 10 ppm/K, especially not more than 8 ppm/K; and
said second material is a metallic material with a coefficient of thermal expansion of no less than 12 ppm/K, especially not less than 14 ppm/K and furthermore no less than 15 ppm/K.

5. The sintered body according to claim 1 , wherein:
the difference between said first coefficient of thermal expansion and said second coefficient of thermal expansion is at a value of no less than 5 ppm/K.

6. The sintered body according to claim 1 , wherein:
said layers in the transition region each have a layer height h of no less than 10 μm, especially no less than 20 μm and preferably no less than 40 μm.

7. The sintered body according to claim 1 , wherein:
the transition region has N layers with each one having a different coefficient of thermal expansion, whose value is between said first coefficient of thermal expansion α 1 and said second coefficient of thermal expansion α 2 ;
and
the number N is no less than (Δα)/(2 ppm/K), especially no less than (Δα)/(1 ppm/K) and preferably no less than (2 Δα)/(1 ppm/K).

8. The sintered body according to claim 7 , wherein:
the sintered body comprises at least sectionally a cylindrical or conical full body or hollow body.

9. The sintered body according to claim 1 , wherein:
said first region has a first planar surface of the sintered body that faces away from said second region;
said second region has a second planar surface of the sintered body that is facing away from said second region; and
said first and said second surface are parallel to the layers of said transition region.

10. A sintered body, comprising:
a first region which has a first material having a first effective coefficient of thermal expansion α 1 ;
a second region which has a second material having a second effective coefficient of thermal expansion α 2 ; and
a transition region between said first region and said second region in which the effective coefficient of thermal expansion changes from said first effective coefficient of thermal expansion to the second effective coefficient of thermal expansion, wherein:
said transition region has a sequence of layers with a mixture of at least said first material and said second material, with the mixing ratio of the layers varying in order to achieve a stepwise, in particular monotonic, change in the coefficient of thermal expansion;
said transition region has a maximum extension d vertically to one direction of the layer sequence, and wherein one layer has an average layer thickness s, whereby the following applies:

d
s

·



Δ
⁢

⁢

α
s



<

ξ
s

,

Δα s is the difference between the effective coefficient of thermal expansion of the layers adjacent to this layer, and whereinξ s is a constant with the dimension 1/K for which the following applies: ξ s <0,1%/K, especially <500 ppm/K, preferably <250 ppm/K, further preferred <125 ppm/K and particularly preferred <60 ppm/K, whereby the following applies:

d
s

·



Δ
⁢

⁢

α
s



<

ξ
s

,

ΔT=(T max −T min ) is the size of a specified temperature range for the sintered body, and with C S being a dimensionless deformation parameter, for which the following applies: C S <4%, especially <2% and preferably <1%.

11. A sintered body, comprising:
a firs

Assignees

• Endress Hauser Gmbh Co Kg

Inventors

• Rossberg Andreas
• Schmidt Elke
• Tham Anh Tuan

Classifications

• B32B2264/105

  Metal · CPC title

• C04B2235/6026

  Computer aided shaping, e.g. rapid prototyping · CPC title

• G01L19/04 Primary

  Means for compensating for effects of changes of temperature {, i.e. other than electric compensation} · CPC title

• B32B18/00

  Layered products essentially comprising ceramics, e.g. refractory products · CPC title

• C04B2237/123

  based on iron group metals, e.g. steel · CPC title