Document:

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                                                                     Exhibit 4.6
                        LIMITED RECOURSE PROMISSORY NOTE

$20,200,000 (U.S.)                                               October 4, 2000

     FOR VALUE RECEIVED, the undersigned, Unifrax Holding Co., a Delaware
corporation (the "HOLDINGS"), hereby promises to pay to Societe Europeenne de
Produits Refractaires, as agent for those Persons identified on Schedule I (the
"PAYEE"), at "Les Miroirs" 18, Avenue d'Alsace, 92096 LA DEFENSE CEDEX, FRANCE,
or at such other place as the Payee may from time to time designate in writing,
in lawful money of the United States of America an aggregate amount equal to
TWENTY MILLION TWO HUNDRED THOUSAND U.S. DOLLARS ($20,200,000) on the terms set
forth below; provided, however, that the aggregate principal amount of this
Promissory Note (this "NOTE") will be permanently reduced by the amount or
amounts, if any, (a) by which the aggregate principal amount of that certain
Subordinated Promissory Note (the "CORPORATION NOTE"), dated the date hereof
issued by Unifrax Corporation (the "CORPORATION") in favor of Payee, in the
initial principal amount of EIGHT MILLION U.S. DOLLARS ($8,000,000) is increased
to a principal amount in excess of EIGHT MILLION U.S. DOLLARS ($8,000,000)
pursuant to the provisions of the first paragraph of the Corporation Note, and
(b) actually paid by the Corporation pursuant to any guaranty of this Note
(each, a "GUARANTY AGREEMENT") provided to Payee by the Corporation after the
date hereof.

     1. INTEREST RATE. This Note will bear, subject to Section 2(b) below,
simple interest on the outstanding principal at an annual rate of (a) 7% from
the date of this Note until December 31, 2001, (b) 8.5% from January 1, 2002
until December 31, 2002, and (c) 10% from January 1, 2003 until June 30, 2004.

     2. PAYMENT.

        (a) Subject to Section 2(b) and Section 5 of this Note or acceleration
     as provided herein, interest is due and payable on January 31, 2001,
     January 31, 2002, January 31, 2003 and June 30, 2004 (each an "INTEREST
     PAYMENT DATE") based on an actual/365 day year and the actual days the
     principal amount hereof is outstanding. Interest on the principal amount of
     the Note will accrue beginning on the date of issuance of this Note and
     will continue to accrue for so long as any principal amount of this Note is
     outstanding.

        (b) In the event that Holdings does not receive the payment in full of
     all dividends to which it is entitled pursuant to ARTICLE FOURTH, Section
     (A)(2) of the Certificate of Amendment of the Certificate of Incorporation
     of the Corporation as a consequence of any provision of any agreements or
     instruments representing or evidencing any Senior Indebtedness (as defined
     in the Corporation Note), Holdings will not be required on any Interest
     Payment Date to make a cash interest payment hereunder, such non-payment
     will not constitute an Event of Default (defined below) hereunder and all
     of such installment (or the unpaid portion thereof) shall be added to the
     principal under this Note.

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        (c) The entire unpaid principal amount of this Note and any accrued
     and unpaid interest due hereon shall become due and payable on June 30,
     2004.

        (d) Whenever any payment to be made under this Note is stated to be
     due on Saturday, Sunday or a legal holiday or the equivalent for banks
     generally under the laws of the State of New York (any other day being a
     "BUSINESS DAY"), such payment may be made on the next succeeding Business
     Day.

     3. PREPAYMENT. This Note may be prepaid by Holdings in whole or in part at
any time without premium or penalty. Any such prepayment shall be first applied
to the payment of accrued but unpaid interest on the principal amount to be
prepaid and then to principal.

     4. PLEDGE. The amounts due under this Note are secured by a pledge of
20,500 shares of Series A Preferred Stock of the Corporation ("PREFERRED STOCK")
pursuant to a Pledge Agreement of even date herewith, by and between Holdings
and the Payee (the "PLEDGE AGREEMENT"). In the event of an Event of Default,
Payee shall have the remedies provided for in the Pledge Agreement. In the event
that the Payee forecloses on the Preferred Stock pursuant to the Pledge
Agreement and such recovery thereunder is less than the amounts then due under
this Note, Holdings will remain liable for such deficiency, provided, however,
that in no event will Payee have any rights to acquire any interest in or
exercise any control over Holdings' interest in the common stock of the
Corporation notwithstanding any right or remedy otherwise available to Payee
under applicable law.

     5. SET-OFF. Holdings has the right to offset against any payment of
interest or principal due and payable (whether by scheduled amortization or
prepayment) from Holdings to the Payee under this Note any amounts owing from
the Payee or any Affiliate (as hereinafter defined) to Holdings or the
Corporation under any of the Transaction Documents (as defined in that certain
Stock and Asset Purchase Agreement by and among Payee, the Corporation and
certain other parties thereto, dated as of July 27, 2000) and any such offset
shall not constitute an Event of Default. In the event of any such offset, the
amount of such offset shall be allocated pro rata among (a) this Note; (b) that
certain Limited Resource Promissory Note, dated the date hereof, in the original
principal amount of $300,000, issued by Holdings in favor of Carborundum do
Brasil, (c) the Corporation Note; (d) that certain Subordinated Promissory Note,
dated the date hereof, in the original principal amount of $1,500,000, issued by
Corporation in favor of SEPR; and (e) any Guaranty Agreement or Guaranty
Agreements in effect at that time.

     6. DEFAULT; ACCELERATION. In the case an Event of Default occurs and is
continuing, the entire unpaid principal of this Note, together with all accrued
but unpaid interest, will become immediately due and payable at the Payee's
option. An "EVENT OF DEFAULT" means (a) the failure of Holdings to make any
payment of interest or principal within fifteen days of the date such payment is
due, other than (i) as provided in Section 2(b) hereof and (ii) in accordance
with Holdings' right to offset against this Note as further described in Section
5 above, or (b) Holdings' filing a petition or otherwise voluntarily commencing
a case or proceeding or filing an answer or other pleading in any proceeding
seeking relief under any federal or state bankruptcy, insolvency or debtors'
reorganization law, being the voluntary or involuntary subject of an order for
relief by any court under any such law, or being adjudicated "bankrupt,"
"debtor" or

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"insolvent" under any such law, or there being appointed under any such law, a
"trustee," "receiver" or "custodian" to manage Holdings' business or properties,
or there being commenced under any such law a case or proceeding proposing such
an order for relief, adjudication or appointment with respect to Holdings or
Holdings' business, which proceeding is consented to by Holdings or that is not
dismissed within 90 days after being commenced, or (c) a Change-in-Control (as
defined below).

     7. NO RECOURSE. No director, stockholder, officer, employee or incorporator
as such, past, present or future of Holdings or any successor person has any
liability for any obligation of Holdings under this Note or for any claim based
on, in respect of or by reason of, any such obligation or its creation. The
Payee by accepting this Note waives and releases all such liability. This waiver
and release are part of the consideration for the issue of this Note.

     8. COSTS. In the event that any principal or interest due hereunder is not
paid in accordance with this Note, Holdings shall pay any and all reasonable
costs incurred by Payee to collect the sums due hereunder, including, but not
limited to, reasonable attorneys' fees and disbursements.

     9. LATE PENALTY. Except as otherwise provided in Section 2(b) and Section 5
of this Note, any payment of interest that is required to be made hereunder that
is not made within fifteen (15) days of the date specified for payment or
otherwise in accordance with this Note shall bear a late fee equal to five
percent (5%) of the amount of the payment then due.

     10. NO WITHHOLDING. Any payments or prepayments to be made in respect of
interest on this Note shall be made without deduction or withholding, or with
such additional amounts as may be necessary in order that Payee, after such
deduction or withholding, receives the full amount of interest then due and
payable or intended to be prepaid.

     11. WAIVER OF DEFENSES. Subject to Section 5 of this Note, Holdings hereby
waives presentment for payment, protest and demand, suretyship defenses and all
other defenses in the nature thereof and notice of non-payment, changes in terms
and conditions and all other indulgences granted by Payee.

     12. NO IMPLIED WAIVER. Payee shall not, by any act, delay, omission or
otherwise, be deemed to waive any of its rights or remedies hereunder, unless
such waiver be in writing and signed by Payee and Holdings, and then only to the
extent expressly set forth therein. A waiver on any such occasion shall not be
construed as a bar to, or waiver of, any such right or remedy on any future
occasion.

     13. GOVERNING LAW; INTERPRETATION. This Note is to be governed and
controlled as to interpretation, enforcement, validity, construction, and in all
other respects by the laws, statutes and decisions of the State of New York.

     14. INVALIDITY. If any one or more of the provisions contained in this Note
are invalid, illegal or unenforceable in any respect, the validity, legality or
enforceability of all the remaining provisions will not in any way be affected
or impaired.

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     15. ASSIGNMENT. The Payee shall not assign, negotiate or otherwise transfer
this Note or any or all of its rights under this Note to any Person without the
prior written consent of Holdings, except to an Affiliate of Payee. This Note
may not be assigned, transferred or pledged, in whole or in part, by Holdings
without the prior written consent of Payee.

     16. CERTAIN DEFINITIONS. As used in this Note, (a) "AFFILIATE" of any
Person means any Person directly or indirectly controlling, controlled by, or
under common control with, any such Person and any officer, director or
controlling Person of such Person, (b) "PERSON" means any individual,
corporation, partnership, limited liability company, joint venture, trust,
governmental authority, unincorporated association or any other entity or
organization, and (c) "CHANGE-IN-CONTROL" means the acquisition by a Person
(other than Kirtland Capital Partners II LP or any Affiliate thereof) of (i) the
ownership or control (directly or indirectly) of more than 50% of the voting
share capital of Holdings or the Corporation or (ii) the right to appoint or
remove directors having a majority of the voting rights exercisable at meetings
of the boards of directors of Holdings or the Corporation.

                   [BALANCE OF PAGE INTENTIONALLY LEFT BLANK]

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     IN WITNESS WHEREOF, Holdings has caused this Note to be duly executed as of
the date first above written.

                                           UNIFRAX HOLDING CO.

                                           By:  /s/  William P. Kelly
                                                -------------------------------
                                                Name:  William P. Kelly
                                                Title:  President

ACKNOWLEDGED AND AGREED
to this __ day of October, 2000

SOCIETE EUROPEENNE DE PRODUITS REFRACTAIRES

By:  /s/ Roland Lazard
     ---------------------------
Name:  Roland Lazard
Title: Senior Vice President Finance

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<PAGE>   6

                                   SCHEDULE I

Carborundum France, SA                                     $2,100,000

Unifrax Limited                                            $10,000,000

Carborundum Deutschland GmbH                               $4,700,000

Carborundum Australia Pty. Ltd.                            $3,400,000

                                       6<PAGE>   1

                                                                     Exhibit 4.7

                        LIMITED RECOURSE PROMISSORY NOTE

$300,000 (U.S.)                                                  October 4, 2000

       FOR VALUE RECEIVED, the undersigned, Unifrax Holding Co., a Delaware
corporation (the "HOLDINGS"), hereby promises to pay to Carborundum do Brasil
(the "PAYEE"), at Vuenida Independencia 7031, Vinhedo, Sao Paulo, Brasil, or at
such other place as the Payee may from time to time designate in writing, in
lawful money of the United States of America an aggregate amount equal to THREE
HUNDRED THOUSAND U.S. DOLLARS ($300,000) on the terms set forth below.

       1.  INTEREST RATE. This Promissory Note (this "NOTE")will bear, subject
       to Section 2(b) below, simple interest on the outstanding principal
       at an annual rate of (a) 7% from the date of this Note until December
       31, 2001, (b) 8.5% from January 1, 2002 until December 31, 2002, and
       (c) 10% from January 1, 2003 until June 30, 2004.

       2.  PAYMENT.

           (a) Subject to Section 2(b) and Section 5 of this Note or
       acceleration as provided herein, interest is due and payable on January
       31, 2001, January 31, 2002, January 31, 2003 and June 30, 2004 (each an
       "INTEREST PAYMENT DATE") based on an actual/365 day year and the actual
       days the principal amount hereof is outstanding. Interest on the
       principal amount of the Note will accrue beginning on the date of
       issuance of this Note and will continue to accrue for so long as any
       principal amount of this Note is outstanding.

           (b) In the event that Holdings does not receive the payment in full
       of all dividends to which it is entitled pursuant to ARTICLE FOURTH,
       Section (A)(2) of the Certificate of Amendment of the Certificate of
       Incorporation of the Corporation as a consequence of any provision of any
       agreements or instruments representing or evidencing any Senior
       Indebtedness (as defined in the Corporation Note), Holdings will not be
       required on any Interest Payment Date to make a cash interest payment
       hereunder, such non-payment will not constitute an Event of Default
       (defined below) hereunder and all of such installment (or the unpaid
       portion thereof) shall be added to the principal under this Note.

           (c) The entire unpaid principal amount of this Note and any accrued
       and unpaid interest due hereon shall become due and payable on June 30,
       2004.

           (d) Whenever any payment to be made under this Note is stated to be
       due on Saturday, Sunday or a legal holiday or the equivalent for banks
       generally under the laws of the State of New York (any other day being a
       "BUSINESS DAY"), such payment may be made on the next succeeding Business
       Day.
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       3. PREPAYMENT. This Note may be prepaid by Holdings in whole or in part
at any time without premium or penalty. Any such prepayment shall be first
applied to the payment of accrued but unpaid interest on the principal amount to
be prepaid and then to principal.

       4. PLEDGE. The amounts due under this Note are secured by a pledge of
20,500 shares of Series A Preferred Stock of the Corporation ("PREFERRED STOCK")
pursuant to a Pledge Agreement of even date herewith, by and between Holdings
and Societe Europeenne de Produits Refractaires ("SEPR") (the "PLEDGE
AGREEMENT"). In the event of an Event of Default, SEPR shall have the remedies
provided for in the Pledge Agreement. In the event that the SEPR forecloses on
the Preferred Stock pursuant to the Pledge Agreement and such recovery
thereunder is less than the amounts then due under this Note, Holdings will
remain liable for such deficiency, provided, however, that in no event will SEPR
have any rights to acquire any interest in or exercise any control over
Holdings' interest in the common stock of the Corporation notwithstanding any
right or remedy otherwise available to SEPR under applicable law.

       5. SET-OFF. Holdings has the right to offset against any payment of
interest or principal due and payable (whether by scheduled amortization or
prepayment) from Holdings to the Payee under this Note any amounts owing from
the Payee or any Affiliate (as hereinafter defined) to Holdings or the
Corporation under any of the Transaction Documents (as defined in that certain
Stock and Asset Purchase Agreement by and among Societe Europeenne de Produits
Refractaires, the Corporation and certain other parties thereto, dated as of
July 27, 2000) and any such offset shall not constitute an Event of Default. In
the event of any such offset, the amount of such offset shall be allocated pro
rata among (a) this Note; (b) that certain Limited Recourse Promissory Note,
dated the date hereof, in the original principal amount of $20,200,000, issued
by Holdings in favor of SEPR; (c) that certain Subordinated Promissory Note,
dated the date hereof, in the original principal amount of $8,000,000, issued by
Corporation in favor of SEPR (the "CORPORATION NOTE"); (d) that certain
Subordinated Promissory Note, dated the date hereof, in the original principal
amount of $1,500,000, issued by Corporation in favor of SEPR; and (e) any
Guaranty Agreement or Guaranty Agreements (each, as defined in the Corporation
Note) in effect at that time.

       6. DEFAULT; ACCELERATION. In the case an Event of Default occurs and is
continuing, the entire unpaid principal of this Note, together with all accrued
but unpaid interest, will become immediately due and payable at the Payee's
option. An "EVENT OF DEFAULT" means (a) the failure of Holdings to make any
payment of interest or principal within fifteen days of the date such payment is
due, other than (i) as provided in Section 2(b) hereof and (ii) in accordance
with Holdings' right to offset against this Note as further described in Section
5 above, or (b) Holdings' filing a petition or otherwise voluntarily commencing
a case or proceeding or filing an answer or other pleading in any proceeding
seeking relief under any federal or state bankruptcy, insolvency or debtors'
reorganization law, being the voluntary or involuntary subject of an order for
relief by any court under any such law, or being adjudicated "bankrupt,"
"debtor" or "insolvent" under any such law, or there being appointed under any
such law, a "trustee," "receiver" or "custodian" to manage Holdings' business or
properties, or there being commenced under any such law a case or proceeding
proposing such an order for relief, adjudication or appointment with respect to
Holdings or Holdings' business, which proceeding is consented to by Holdings or
that is not dismissed within 90 days after being commenced, or (c) a
Change-in-Control (as defined below).

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<PAGE>   3

       7. NO RECOURSE. No director, stockholder, officer, employee or
incorporator as such, past, present or future of Holdings or any successor
person has any liability for any obligation of Holdings under this Note or for
any claim based on, in respect of or by reason of, any such obligation or its
creation. The Payee by accepting this Note waives and releases all such
liability. This waiver and release are part of the consideration for the issue
of this Note.

       8. COSTS. In the event that any principal or interest due hereunder is
not paid in accordance with this Note, Holdings shall pay any and all reasonable
costs incurred by Payee to collect the sums due hereunder, including, but not
limited to, reasonable attorneys' fees and disbursements.

       9. LATE PENALTY. Except as otherwise provided in Section 2(b) and Section
5 of this Note, any payment of interest that is required to be made hereunder
that is not made within fifteen (15) days of the date specified for payment or
otherwise in accordance with this Note shall bear a late fee equal to five
percent (5%) of the amount of the payment then due.

       10. NO WITHHOLDING. Any payments or prepayments to be made in respect of
interest on this Note shall be made without deduction or withholding, or with
such additional amounts as may be necessary in order that Payee, after such
deduction or withholding, receives the full amount of interest then due and
payable or intended to be prepaid.

       11. WAIVER OF DEFENSES. Subject to Section 5 of this Note, Holdings
hereby waives presentment for payment, protest and demand, suretyship defenses
and all other defenses in the nature thereof and notice of non-payment, changes
in terms and conditions and all other indulgences granted by Payee.

       12. NO IMPLIED WAIVER. Payee shall not, by any act, delay, omission or
otherwise, be deemed to waive any of its rights or remedies hereunder, unless
such waiver be in writing and signed by Payee and Holdings, and then only to the
extent expressly set forth therein. A waiver on any such occasion shall not be
construed as a bar to, or waiver of, any such right or remedy on any future
occasion.

       13. GOVERNING LAW; INTERPRETATION. This Note is to be governed and
controlled as to interpretation, enforcement, validity, construction, and in all
other respects by the laws, statutes and decisions of the State of New York.

       14. INVALIDITY. If any one or more of the provisions contained in this
Note are invalid, illegal or unenforceable in any respect, the validity,
legality or enforceability of all the remaining provisions will not in any way
be affected or impaired.

       15. ASSIGNMENT. The Payee shall not assign, negotiate or otherwise
transfer this Note or any or all of its rights under this Note to any Person
without the prior written consent of Holdings, except to an Affiliate of Payee.
This Note may not be assigned, transferred or pledged, in whole or in part, by
Holdings without the prior written consent of Payee.

       16. CERTAIN DEFINITIONS. As used in this Note, (a) "AFFILIATE" of any
Person means any Person directly or indirectly controlling, controlled by, or
under common control with, any such Person and any officer, director or
controlling Person of such Person, (b) "PERSON" means any

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individual, corporation, partnership, limited liability company, joint venture,
trust, governmental authority, unincorporated association or any other entity or
organization, and (c) "CHANGE-IN-CONTROL" means the acquisition by a Person
(other than Kirtland Capital Partners II LP or any Affiliate thereof) of (i) the
ownership or control (directly or indirectly) of more than 50% of the voting
share capital of Holdings or the Corporation or (ii) the right to appoint or
remove directors having a majority of the voting rights exercisable at meetings
of the boards of directors of Holdings or the Corporation.

                   [BALANCE OF PAGE INTENTIONALLY LEFT BLANK]

                                       4
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       IN WITNESS WHEREOF, Holdings has caused this Note to be duly executed as
of the date first above written.

                                            UNIFRAX HOLDING CO.

                                            By: /s/ William P. Kelly
                                                ----------------------
                                                Name: William P. Kelly
                                                Title: President

ACKNOWLEDGED AND AGREED
to this 4th day of October, 2000

CARBORUNDUM DO BRASIL

By: /s/ Roland Lazard
    -----------------
Name: Roland Lazard
Title:

                                       5

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