HardwareBackButtonManager Service for Ionic (Angular.js) provides an interface to easily enable or disable the hardware back button on Android

Angular.Ionic.HardwareBackButtonManager.js

.service( 'HardwareBackButtonManager', function($ionicPlatform){
  this.deregister = undefined;

  this.disable = function(){
    this.deregister = $ionicPlatform.registerBackButtonAction(function(e){
	e.preventDefault();
	return false;
    }, 101);
  }

  this.enable = function(){
    if( this.deregister !== undefined ){
      this.deregister();
      this.deregister = undefined;
    }
  }
  return this;
})

// usage
.controller( 'YourController', function( 'HardwareBackButtonManager' ){
	HardwareBackButtonManager.disable();
	
	// re-enable it when you want,
	HardwareBackButtonManager.enable();
})