A resistor element for extreme temperatures

SWEDEN (12) PATENT WRITING (13) C2 <11) 516 644

<img file="SE516644C2_D0001.tif" />

(19) SE (51)

International class ⁷

H05B 3/14, C04B 35/58, 35/565, C22C 29/02, 29/18

PATENT AND REGISTRATION AGENCY (45) (41) (22) (24) (62) (86) (86) (83)

Patent announced Application publicly available The patent application was received on the maturity date

The number of the main application

2002-02-05

2002-02-05

2000-12-21

2000-12-21 (21) Patent application number Q004819-9

Application received as:

International filing date Filing date for application for European patent Deposit of microorganism Swedish patent application completed international patent application with number □ converted European patent application with number (30) Priority information (73) (72) (74) (54) (56) (57)

PATENTHAVARE Sandvik AB, 811 81 Sandviken SE

INVENTOR Mats Sundberg, Västerås SE, Chet Popilowski,

Washington CT

US

AGENT Nore'ns Patentbyrå AB

DESIGNATION Resistance element for extreme temperatures

PROMISED PUBLICATIONS: - - SUMMARY:

Electrical resistance element for heating.

According to the invention, the element consists mainly of titanium silicon carbide (Ti₃Sic₂ ) .

The numbers in parentheses indicate international identification code, INID code. Letter in parentheses indicates international document code.

f PRV Patent uses the following document codes for its patents

<td>code</td><td>cleartext</td><td>code</td><td>cleartext</td>

<td>A</td><td>publicly available patent application</td><td>L</td><td>publicly available</td>

<td>B</td><td>spelling *</td><td>TI</td><td>translation of the requirements of the European patent application</td>

<td>B5</td><td>corrected spelling *</td><td>T2</td><td>correction of the translation of the requirements of the European patent application</td>

<td>C</td><td>patent specification *</td><td>T3</td><td>translation of European patent specification</td>

<td>Cl</td><td>patent specification *</td><td>T4</td><td>translation of European patent specification in amended version</td>

<td>C2</td><td>patent</td><td>T5</td><td>corrected translation of European patent specification</td>

<td>C3</td><td>corrected patent specification</td><td>T8</td><td>corrected translation of European patent specification</td>

<td>C5</td><td>corrected patent specification *</td><td>T9</td><td>corrected translation of European patent specification</td>

<td>C8</td><td>corrected front page to patent specification</td><td></td><td></td>

<td>E</td><td>patent specification in amended wording</td><td></td><td></td>

<td>E8</td><td>corrected front page to patent specification in amended wording</td><td></td><td></td>

<td>E9</td><td>corrected patent specification in amended wording</td><td colspan="2">* published under older legislation in</td>

fNationskoder

<td>AP</td><td>African Regional</td><td>CN</td><td>China</td><td>Kl Kiribati</td><td>RU</td><td>Russian Federation</td>

<td></td><td>Industrial Property</td><td>CO</td><td>Colombia</td><td>KM Comorema</td><td>RW</td><td>Ruanda</td>

<td></td><td>Organization (ARIPO)</td><td>CR</td><td>Costa Rica</td><td>KN St Kitts</td><td>SA</td><td>Saudi Arabia</td>

<td>EA</td><td>Euroasian Patent Office</td><td>CU</td><td>Cuba</td><td>KP Dem. People's Republic of Korea</td><td>SB</td><td>Salomonöama</td>

<td></td><td>(EAPO)</td><td>CV</td><td>Cape Verde</td><td>KR Republic of Korea</td><td>SC</td><td>Seychelles</td>

<td>EP</td><td>European Patent Office</td><td>CY</td><td>Cyprus</td><td>KW Kuwait</td><td>SD</td><td>sudan</td>

<td></td><td>(EPO)</td><td>CZ</td><td>The Czech Republic</td><td>KY Cayman Island</td><td>SEE</td><td>Sweden</td>

<td>OA</td><td>African Intellectual</td><td>THE</td><td>Germany</td><td>KZ Kazakhstan</td><td>SG</td><td>singapore</td>

<td></td><td>Property Organization</td><td>DJ</td><td>djibouti</td><td>LA Laos</td><td>SH</td><td>St Helena</td>

<td></td><td>(O.API)</td><td>DK</td><td>Denmark</td><td>LB Lebanon</td><td>SI</td><td>Slovenia</td>

<td>WO</td><td>World Intellectual</td><td>DM</td><td>dominica</td><td>LC Saint Lucia</td><td>SK</td><td>Slovakia</td>

<td></td><td>Property Organization</td><td>DO</td><td>Dominican Republic</td><td>Ll Liechtenstein</td><td>SL</td><td>Sierra Leone</td>

<td></td><td>(WIPO)</td><td>DZ</td><td>Algeria</td><td>LK Sri Lanka</td><td>SM</td><td>San Marino</td>

<td>IB</td><td>WIPO (in some cases)</td><td>EC</td><td>Ecuador</td><td>LR Liberia</td><td>SN</td><td>senegal</td>

<td></td><td></td><td>EE</td><td>Estonia</td><td>LS Lesotho</td><td>SE</td><td>somalia</td>

<td>A.D</td><td>Andorra</td><td>EC</td><td>Egypt</td><td>LT Lithuania</td><td>SR</td><td>Suriname</td>

<td>AE</td><td>United Arab Emirates</td><td>ES</td><td>Spain</td><td>LU Luxembourg</td><td>ST</td><td>Säo Thomé</td>

<td>AF</td><td>Afghanistan</td><td>ET</td><td>Ethiopia</td><td>LV Latvia</td><td>EN</td><td>El Salvador</td>

<td>AG</td><td>Antigua</td><td>FI</td><td>Finland</td><td>LY Libya</td><td>SEW</td><td>Syria</td>

<td>AI</td><td>Anguilla</td><td>FJ</td><td>Fiji islets</td><td>MA Morocco</td><td>SZ</td><td>swaziland</td>

<td>AL</td><td>Albania</td><td>FK</td><td>Falklandsöama</td><td>MC Monaco</td><td>TD</td><td>Chad</td>

<td>AM</td><td>Armenia</td><td>FR</td><td>France</td><td>MD Moldova</td><td>TG</td><td>togo</td>

<td>AN</td><td>Netherlands Antilles</td><td>GA</td><td>Gabon</td><td>MG Madagascar</td><td>TH</td><td>thailand</td>

<td>AO</td><td>angola</td><td>GB</td><td>UK</td><td>MK Macedonia</td><td>TJ</td><td>Tajikistan</td>

<td>ARE</td><td>Argentina</td><td>DG</td><td>grenada</td><td>ML Mali</td><td>TM</td><td>turkmenistan</td>

<td>AT</td><td>Austria</td><td>GIVE</td><td>Georgia</td><td>MM Mayanmar</td><td>TN</td><td>Tunisia</td>

<td>AU</td><td>Australia</td><td>GH</td><td>Ghana</td><td>MN Mongolia</td><td>TO</td><td>tonga</td>

<td>AZ</td><td>Azerbaijan</td><td>GI</td><td>Gibraltar</td><td>MR Mauritania</td><td>TR</td><td>Turkey</td>

<td>BA</td><td>Bosnia and</td><td>GM</td><td>gambia</td><td>MS Monsterrat</td><td>TT</td><td>Trinidad and Tobago</td>

<td></td><td>Herzegovina</td><td>GN</td><td>guinea</td><td>MT Malta</td><td>TV</td><td>Tuvalu</td>

<td>BB</td><td>barbados</td><td>GQ</td><td>Equatorial Guinea</td><td>MU Mauritius</td><td>TW</td><td>taiwan</td>

<td>BD</td><td>bangladesh</td><td>GR</td><td>Greece</td><td>MV Maldivema</td><td>TZ</td><td>Tanzania</td>

<td>ASK</td><td>Belgium</td><td>GT</td><td>Guatemala</td><td>MW Malawi</td><td>UA</td><td>Ukraine</td>

<td>BF</td><td>Burkina Faso</td><td>GW</td><td>Guinea Bissau</td><td>MX Mexico</td><td>UG</td><td>uganda</td>

<td>BG</td><td>Bulgaria</td><td>GY</td><td>guyana</td><td>MY Malaysia</td><td>US</td><td>United States (USA)</td>

<td>BH</td><td>bahrain</td><td>HK</td><td>Hong Kong</td><td>MZ Mozambique</td><td>UY</td><td>uruguay</td>

<td>BI</td><td>Burundi</td><td>HN</td><td>honduras</td><td>NA Namibia</td><td>UZ</td><td>uzbekistan</td>

<td>BJ</td><td>benin</td><td>HR</td><td>Croatia</td><td>NG Nigeria</td><td>VA</td><td>Vatican City</td>

<td>BM</td><td>bermuda</td><td>HT</td><td>Haiti</td><td>NI Nicaragua</td><td>VC</td><td>St Vincent</td>

<td>STAY</td><td>bolivia</td><td>HU</td><td>Hungary</td><td>NL Netherlands</td><td>VE</td><td>venezuela</td>

<td>BR</td><td>Brazil</td><td>ID</td><td>Indonesia</td><td>NO Norge</td><td>VG</td><td>Virgin Islands</td>

<td>BS</td><td>The Bahamas</td><td>IU</td><td>Ireland</td><td>NP Nepal</td><td>VN</td><td>Viet Nam</td>

<td>BT</td><td>Bhutan</td><td>IL</td><td>israel</td><td>NR Nauru</td><td>VU</td><td>vanuatu</td>

<td>BW</td><td>Botswana</td><td>IN</td><td>India</td><td>NZ New Zealand</td><td>ws</td><td>Samoa</td>

<td>VILLAGE</td><td>Belarus</td><td>IQ</td><td>Iraq</td><td>OM Oman</td><td>YD</td><td>South Yemen</td>

<td>BZ</td><td>belize</td><td>IR</td><td>Iran</td><td>PA Panama</td><td>YE</td><td>Yemen</td>

<td>CA</td><td>Canada</td><td>ICE</td><td>Iceland</td><td>PE Peru</td><td>YU</td><td>Yugoslavien</td>

<td>CF</td><td>central African</td><td>IT</td><td>Italy</td><td>PG Papua New Guinea</td><td>ZA</td><td>South Africa</td>

<td></td><td>Republic</td><td>JM</td><td>jamaica</td><td>PH Philippines</td><td>ZM</td><td>Zambia</td>

<td>CG</td><td>Congo</td><td>YES</td><td>Jordan</td><td>PK Pakistan</td><td>ZR</td><td>Zaire</td>

<td>CH</td><td>Switzerland</td><td>JP</td><td>Japanese</td><td>PL Poland</td><td>ZW</td><td>zimbabwe</td>

<td>Cl</td><td>iVORY COAST</td><td>KE</td><td>Kenya</td><td>PT Portugal</td><td></td><td></td>

<td>CL</td><td>Chile</td><td>KG</td><td>Kyrgyzstan</td><td>PY Paraguay</td><td></td><td></td>

<td>CM</td><td>Cameroon</td><td>KH</td><td>Cambodia</td><td>RO Romania</td><td></td><td></td>

516 644

The present invention relates to a new electrical resistance heating element for extremely high temperatures.

The heating element is intended for use in connection with heat treatment and sintering in inert and reducing atmospheres and also oxidizing atmospheres and under vacuum up to extremely high temperatures such as 2300 ° C.

Resistance elements of the present type are manufactured by the applicant, such as resistance elements based on NiCr, FeCrAl, SiC and MoSi2. These materials are used in a variety of atmospheres and at different temperatures. What these materials have in common is that their usefulness at high temperatures, ie above 1300 ° C, is limited in reducing environments and under vacuum. For temperatures up to over 2000 ° C, heating elements are mainly used of Mo, W, Ta (tantalum) and graphite. These materials each have disadvantages and limitations, the common one being that the materials oxidize easily when used above 400 - 500 ° C, which means that special consideration must be given to oven design and operation. The high specific gravity of Ta, Mo and W also constitutes limitations with regard to mechanical construction. Furthermore, the material cost itself is high for refractory metals.

The present invention provides resistance elements of a new material.

The present invention thus relates to an electric resistance element for heating, which is characterized in that the element consists mainly of titanium silicon carbide (Ti₃Sic₂ ) .

G: \ Ansokn00 \ 000145se.tr.rätt.doc, 2001-12-12

516 644

According to the invention, the element consists mainly of titanium silicon carbide (Ti₃Sic₂ ) .

The element can consist of Ti₃SiC2 to close to 100% by weight.

According to a preferred embodiment, the element consists of at least 85% by weight of titanium silicon carbide.

According to a preferred embodiment, the material contains up to 15% by weight of one or more of the compounds TiC, TiSi₂ , Ti₅Si₃ or SiC, and thus as at least 85% by weight of titanium silicon carbide.

Titanium silicon carbide in its pure form is a fairly new ceramic material which exhibits, among other things, very good mechanical and thermal properties.

The material is for the texture of the type a so-called nanolaminate, which contributes to very good impact resistance and high thermal shock resistance. The material can, which is unique to a ceramic material, be easily processed and can e.g. cut with a jigsaw.

The material is relatively light with a density of 4.5 g / cm3. The thermal conductivity is fairly constant with the temperature around 35 W / mK and the material is also a good electrical conductor.

The material can be plastically deformed at high temperatures.

The creep properties exceed those of so-called superalloys used up to 1100 ° C, which in no way constitutes an upper temperature limit for Ti₃Sic₂.

G: \ Ansokn00 \ 000145se.tr.rätt.doc, 2001-12-12

516 644

A very essential property is that the oxidation properties of Ti₃Sic₂ exceeds the oxide properties of Mo, W, Ta (tantalum) and graphite.

Material Ti₃Sic₂ exists up to 2330 ° C. At this temperature it decomposes to TiC_x and Si. This thus sets a practical limit of 2300 ° C in use.

Until recently, the properties of a phase-clean material were Ti₃Sic₂ rather unknown due to the difficulty of producing such a material.

Measurements of electrical resistance on tightly sintered wire made of Ti powder₃Sic₂ under the argon atmosphere in the temperature range 20-1600 ° C showed that the resistance of the material within this range varies linearly from approx. 0.28 ohm * mm2 / m to approx. 1.43 ohm * mm²/ M. This is on a par with MoSi₂-heating element at room temperature, but is approx. 55% lower than for MoSi₂heating element at 1600 ° C.

It has been found that the stability of the material is favored by lower and lower partial pressures of oxygen, which shows that the material can be successfully used in vacuum furnaces under high vacuum where low degassing rate from the heaters is essential.

It has also surprisingly been found that the material remains unaffected during exposure to dry hydrogen up to at least 1800 ° C. This is the maximum temperature at which experiments were performed, but it is likely that the material is stable in dry hydrogen up to even higher temperatures.

Titanium silicon carbide also exhibits very good properties in oxidizing atmospheres, such as air, up to 1100-1200 ° C. Hereby

G: \ Ansokn00 \ 000l45se.tr.rätt.doc, 2001-12-12

516 644 the surface oxide of the element consists of TiO₂. Inside the surface oxide are oxides in the form of SiO₂-Ten₂. However, the properties of titanium silicon carbide in the oxidizing atmosphere at these and higher temperatures are exceeded by FeCrAl and MoSi alloys.₂. These materials are manufactured by the applicant in a variety of designs under the KANTHAL and KANTHAL SUPER brands. Ti3SiC₂ thus does not constitute a better alternative to these alloys in an oxidizing environment.

Titanium silicon carbide also resists relatively long times during oxidation up to 1700 ° C in air compared to elements of Mo, W, Ta (tantalum) and graphite. This property means that the material is not consumed for a short time if an inert or reducing atmosphere for some reason can not be maintained in the oven.

In summary, it can be said that the resistive element according to the invention is particularly suitable for use in vacuum, inert or reducing atmospheres up to 2300 ° C and in oxidizing atmospheres up to about 1200 ° C.

Ovens equipped with Ti₃Sic₂-heat elements do not necessarily have a gas-tight enclosure that counteracts oxidation because the material is significantly more oxidation-resistant than Ta, Mo, W and graphite. This facilitates the oven construction.

In comparison with graphite heating elements which are also used in a vacuum and inert and reducing atmosphere, the mechanical strength of Ti is significantly higher.₃Sic₂.

An additional clear advantage of Ti₃Sic₂ is that relatively thin heating elements can be manufactured. Thus, the electrical resistance can be kept high, which means a not too low voltage on the element. In comparison with Mo and W, Ti exhibits₃Sic₂

G: \ Ansokn00 \ 000145se.tr.rätt.doc, 2001-12-12

516 644 about six times higher electrical resistance at room temperature, which means that the cost of the required control and regulation equipment will be lower.

Heating element of Ti₃Sic₂ can be manufactured in a variety of designs such as: rods, pipes, crucibles (with or without electrode pattern), thin layers with electrode pattern (of the hob or surface heater type), plates, strips. For example, elements can be manufactured in rods and U-shaped and provided with coarser connection parts in the same way as is the case for elements of the MoSi2 type. Thin layers with electrode patterns are an alternative to the conventional filament type heating element design.

The good machinability of Ti₃Sic₂ means that complicated geometries with simple means can be performed at a low cost.

In addition to the area of ​​use as a heating element, Ti can₃Sic₂ can also be used in ovens for various purposes, such as carrier materials for goods, heat shields, oven rolls and beams, mufflers, hanger belts and chains, as well as bushings, as well as oven lining.

G: \ Ansokn00 \ 000145se.tr.rätt.doc, 2001-12-12

516 644