001 Front Cover

Manufacturing, Engineering and Sales Since lg38

.*-*N Iffi:*S ffiNW

il: s a les@as ri c h a rds. co m

Phone: 017-527-4385

Fax: 6 I 7-9 64-3 746

E- M a

Ceramic Protection Tubes- Alumina, Mullite, ?hd Zarconia Alumina Alumina has a maximum service temperature of 3450'F (1900"C) in both oxidizing and reduc- ing atmospheres. Alumina is considered to have better mechanical strength (twice the tensile strength of Mullite) and chemical resistance than Mullite. Alumina tubes also have excellent abra- sion resistance. Secondary metal tubes can be added for additional protection from mechanical damage. Alumina tubes are considered gas tight so they make excellent primary protection tubes. All tubes, which are used in horizontal installa- tions and at elevated temperatures, should be supported. Alumina tubes can be used for pri- mary and secondary protection tubes on noble metal (platinum based) thermocouples. Since they have a very low silica content, they will not contaminate platinum elements above 2200"F (1200"C) as a mullite protection tube. Composition - 99.87o Aluminum Oxide. Mullite Porcelain Mullite has a maximum service temperature of 2900"F (1590"C). lt is considered to be better than Alumina for thermal shock resistance. Mullite tubes should be used with care, since they have poor mechanical shock resistance. Secondary metal tubes can be added for protec- tion from mechanical damage. Mullite tubes are considered gas tight at high temperatures. All tubes, which are used in horizontal installations and at elevated temperatures, should be support- ed. Mullite tubes should not be used for primary protection tubes on noble metal (platinum based) thermocouples if the temperature will exceed 2200'F (1200"C). Above these temperatures the silica in the Mullite can contaminate the platinum element if there is not enough air circulation in the tube. Composition - 63.5% Aluminum Oxide, Balance Silicon Dioxide. Zitconia Zirconia has a maximum service temperature of 4172'F (2300"C) in oxidizing, reducing, and vacuum environments. This material is yttria (10.5%) stabilized. Zirconia in chemically inert and has excellent corrosion resistance . Zirconia tubes should not be used in contact with Alumina above 1112"F (600"C). Zuconia is gas tight, but above 1112"F (600"C) Oxygen will permeate through its structure. To prevent thermal shock heat or cool at arate less than 302"F (150'C) pei hour. Composition - 89.5o/o Zirconia, 10.5o/o Yttria.

P

N.nY

"$Y'l'

|

PIaln

P

2

P

N\W W

3

Target Tabe

P

4

P08F and smaller P

SteI FIfrIng

ffiffi W HexFIfrIng

P

5

P

(t

SwIflIpple

7

AIIoytlpple

nLtlpplc

Page 1 01

Visit our Web site At www.AsRtcHARDs.coM @ @