We claim as our invention:
1. A postage meter machine for franking postal items, comprising:
a control unit for controlling at least one component for printing a postage imprint on an item, said control unit having access to at least one item of security information selected from the group consisting of security functions and security data for use in controlling at least one component;
a storage medium having an encrypted access code stored thereon;
a reader unit which interacts with said storage medium to read said encrypted access code therefrom;
an input unit for entering an unencrypted security code; and
a security module in communication with said control unit, said reader unit and said input unit, said security module having an encryption algorithm stored therein for encrypting said unencrypted security code to produce an encrypted security code, and a comparison unit for comparing said encrypted security code to said encrypted access code, said security module allowing access by said control unit to said security information only if said encrypted security code agrees with said encrypted access code in said comparison unit.
2. A postage meter machine as claimed in claim 1 wherein said security module forms said encrypted security code from a user identification and a user password entered through said input unit.
3. A postage meter machine as claimed in claim 2 wherein said security module employs said user password as a key in said encryption algorithm for encrypting said user identification to form said encrypted security code.
4. A postage meter machine as claimed in claim 1 wherein said security module employs a standard encryption algorithm as said encryption algorithm.
5. A postage meter machine as claimed in claim 1 wherein said control unit operates in combination with said storage medium for performing procedures selected from the group consisting of reading said security information, writing said security information, deleting said security information and modifying said security information, and wherein a storage medium having said encrypted access code is required in said reader for allowing said control unit to perform said procedures.
6. A method for protecting security information in a postage meter machine against unauthorized access comprising the steps of:
controlling at least a printer with a control unit, for printing a postage imprint, and making use of security information in said control unit for controlling at least said printer;
entering an unencrypted security code into said postage meter machine;
storing an encrypted access code on a storage medium separable from said postage meter machine;
interacting said storage medium with a reader unit to read said encrypted access code therefrom into said postage meter machine;
encrypting said unencrypted security code to form an encrypted security code in a security module;
supplying said encrypted access code from said reader unit to said security module and, in said security module, comparing said encrypted security code with said encrypted access code; and
allowing said control unit access to said security information only if said security module determines that said encrypted access code agrees with said encrypted security code.
7. A method as claimed in claim 6 comprising entering a user identification and a user password into said postage meter machine and, in said security module, producing said encrypted security code by operating on said user identification with an encryption algorithm using said user password as an encryption key.
8. A method as claimed in claim 7 comprising using a standard encryption algorithm as said encryption algorithm.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A composite material comprising at least about 50 volume percent boride or carbide, the composite material comprising a ceramic portion having alumina and an aluminum alloy made by:
a. contacting a silica-bonded boride- or carbide-based preform with a molten aluminum alloy comprising between about 18 weight percent and about 95 weight percent silicon;
b. allowing reaction between the aluminum and the silica in the preform to go substantially to completion; and
c. removing the composite material from contact with the molten metal.
2. The composite material of claim 1, wherein the material is substantially non-reactive with aluminum.
3. The composite material of claim 1, wherein the ceramic portion comprises silicon carbide, boron carbide, or titanium diboride, or mixtures thereof.
4. The composite material of claim 3, wherein the ceramic portion comprises particulate silicon carbide having an average diameter of between about 5 micrometers and about 5000 micrometers.
5. The composite material of claim 1, comprising at least 50 volume percent carbide particles.
6. The composite material of claim 5, comprising at least 60 volume percent carbide particles.
7. The composite material of claim 1, comprising between about 50 and 90 volume percent carbide, between about 32 and 7 volume percent aluminum oxide, and between about 18 and 3 volume percent aluminum.
8. The composite material of claim 1, comprising an essentially continuous ceramic portion.
9. The composite material of claim 1, comprising less than about five weight percent silica.
10. The composite material of claim 9, comprising less than about one weight percent silica.
11. The composite material of claim 1, wherein the density of the preform is at least about 75 volume percent.
12. The composite material of claim 11, wherein the density of the preform is at least about 85 volume percent.
13. The composite material of claim 1, wherein the composite material is made from a preform that is sufficiently free of interstitial cavities to promote formation of composite material without travel of reactants through interstitial cavities.
14. The composite material of claim 1, wherein the composite material is made from a preform that is substantially totally immersed in molten aluminum alloy.
15. An article comprising the composite material of claim 1.
16. The article of claim 15, wherein the article is capable of contact with molten aluminum without significant reaction with the aluminum.
17. The article of claim 16, wherein the article is selected from the group consisting of riser tubes, diesmolds, heater immersion tubes, thermocouple protection tubes, ladles, and stirring devices.
18. The article of claim 15, wherein the article has one or more surfaces to be exposed to friction or wear.
19. The article of claim 18, wherein the article is selected from the group consisting of bearings, nozzles, bushings, valve components, liners, brake components, clutches, engine components, and turbine components.
20. The article of claim 15, wherein the article is an electrical conductor.
21. The article of claim 20, wherein the article is selected from the group consisting of electric motor brushes, high temperaturehostile environment sensors, high temperaturehostile environment probes, electrodes, and current collectors.
22. The article of claim 15, wherein the article is a thermal management device.
23. The article of claim 22, wherein the article is selected from the group consisting of heat spreaders, heat sinks, thermal diffusers, and substrates.
24. The article of claim 15, wherein the article absorbs and dissipates kinetic energy from high velocity projectiles.
25. The article of claim 15, wherein the article is in substantially the same shape and size as the preform.
26. The article of claim 15, wherein the article is selected from the group consisting of riser tubes, molds, heater immersion tubes, thermocouple protection tubes, bearings, nozzles, bushings, valve components, liners, electric motor brushes, high temperaturehostile environment sensors, high temperaturehostile environment probes, electrodes, current collectors, and armor.
27. A ceramicmetal composite material comprising a ceramic portion comprising silicon carbide and boron carbide, and an alumina-aluminum binding phase, wherein the composite material has been substantially fully reacted with aluminum, and wherein the ceramic portion is formed from a preform comprising about 50 volume percent silicon carbide, about 15 volume percent boron carbide, and about 35 volume percent silica.